Latin is an inflected language, and as such its nouns, pronouns, and adjectives must be declined in order to serve a grammatical function. A set of declined forms of the same word pattern is called a declension. There are five declensions, which are numbered and grouped by ending and grammatical gender. For simple declension paradigms, visit the Wiktionary appendices: Appendix:Latin first declension, Appendix:Latin second declension, Appendix:Latin third declension, Appendix:Latin fourth declension, Appendix:Latin fifth declension.

Grammatical cases

A complete Latin noun declension consists of seven grammatical cases: nominative, vocative, accusative, genitive, dative, ablative, and locative.

This sequence (NOM-VOC-ACC-GEN-DAT-ABL-LOC) has been the usual order taught in Britain and many Commonwealth countries since the publication of Hall Kennedy's Latin Primer (1866). It reflects the tendencies of different cases to share similar endings (see Syncretic trends below). For a discussion of other sequences taught elsewhere, see Instruction in Latin#Order of cases.

Comparisons to English usage

• The nominative case marks the subject of a statement and is also used with a copula: "Mary is going to the store" or "Mary is my sister".
• The genitive case expresses possession, measurement, or source. In English, the genitive case is represented analytically by the preposition of or by the enclitic "–'s", which itself developed from the genitive case. This "–'s" closely resembles the Latin third declension's genitive suffix "–is".
• The dative case marks the recipient of an action, the indirect object of a verb. In English, the prepositions to, from and for tend to denote this case analytically.
• The accusative case marks the direct object of a verb. In English, except for a small number of words which display a distinct accusative case (e.g., who/whom, I/me, he/him), the accusative and nominative cases are identical.
• The ablative case expresses separation, indirection, or the means by which an action is performed. In English, the prepositions by, with, from, in and on are most commonly used to indicate this case.
• The vocative case is used to address someone or something in direct speech. In English, this function is expressed by intonation or punctuation: "Mary, are you going to the store?" or "Mary!" ("Mary" is vocative). Historically, English-language noun paradigms translated this case with a prefaced interjection such as "O Mary!"
• The locative case expresses the place where or time when an action is performed. The Latin locative case is extremely marginal, applying only to the names of cities and small islands and to a few other isolated words. The Romans considered all islands to be "small" except for Sicily, Sardinia, Corsica, Crete, and Cyprus. Much of the case's function had been absorbed into the ablative. For singular first and second declension, the locative is identical to the genitive singular form, and for the singular third declension the locative is identical to the ablative singular form. For plural nouns of all declensions, the locative is also identical to the ablative form. The few fourth and fifth declension place-name words would also use the ablative form for locative case. However, there are a few rare nouns that use the locative instead of a preposition: Domus-->Domī (at home), Rūs-->Rūrī (in the country), Humus-->Humī (on the ground), Militia-->Militiae (in military service, in the field), Focus--> Focī (at the hearth; at the center of the community). In archaic times, the locative singular of third declension nouns was actually interchangeable between ablative and dative forms, but in the Augustan Period the use of the ablative form became fixed.

Syncretic trends

Syncretism, where one form in a paradigm shares the ending of another form in the paradigm, is common in Latin. The following are the most notable patterns of syncretism:

• The vocative is always identical to the nominative in the plural, and also in the singular except in the second declension and a few Greek nouns. For example, the vocative of Aeneās is Aenea, although Aeneās is first declension.
• The dative is always the same as the ablative in the plural, and in the singular in the second declension, the third-declension full i-stems i.e. neuter i-stems, adjectives), and fourth-declension neuters.
• The genitive singular is the same as the nominative plural in first-, second-declension, and fourth declension nouns that are not neuter.
• The dative singular is the same as the genitive singular in first- and fifth-declension nouns.
• Plural neuter nominative/accusative always ends in -a (with a few exceptions: demonstrative hic and related istic and illic, relative/interrogative quī and friends; in all of them, the neuter plural takes the same form as feminine singular nominative).
• The accusative singular ends in short vowel plus -m, except for a few neuters with unusual base forms.
• The accusative plural (assuming not neuter) ends in a long vowel plus -s; so does the nominative plural of the third, fourth and fifth declensions (again assuming not neuter).
• The locative is identical to the ablative in the fourth and fifth declension.
• The locative, ablative, and dative are identical in the plural.

History of cases

Old Latin had only two patterns of endings. One pattern was shared by the first and second declensions, with a clear similarity to the first and second declensions of Ancient Greek. The other pattern was used by the third declension and was very different from Greek, even for direct cognates. When new words were absorbed into Latin, they were generally placed in the third declension.

Nouns

First declension (a)

Nouns of this declension usually end in –a and are typically feminine, e.g. 'road' (via, viae fem.) and 'water' (aqua, aquae fem.). There is a small class of masculine exceptions generally referring to occupations, e.g. 'farmer' (agricola, agricolae masc.) and 'sailor' (nauta, nautae masc.).

The predominant letter in the ending forms of this declension is a. The nominative singular form consists of the stem and the affix -a, and the genitive singular form is the stem plus -ae.

First declension Greek nouns

The first declension also holds three types of Greek nouns, derived from Ancient Greek's Alpha Declension. They are declined irregularly in the singular, but are sometimes treated as if they were native Latin nouns, e.g. nominative athlēta instead of the original athlētēs.

For full paradigm tables and more detailed information, see the Wiktionary appendix Appendix:Latin first declension.

• (First Declension Latin Nouns)

	'aqua, -ae water f.				'agricola, -ae farmer m.
	Singular		Plural		Singular		Plural
Nominative	aqua	–a	aquae	–ae	agricola	–a	agricolae	–ae
Genitive	aquae	–ae	aquārum	–ārum	agricolae	–ae	agricolārum	–ārum
Dative	aquae	–ae	aquīs	–īs	agricolae	–ae	agricolīs	–īs
Accusative	aquam	–am	aquas	–ās	agricolam	–am	agricolas	–ās
Vocative	aqua	–a	aquae	–ae	agricola	–a	agricolae	–ae
Ablative	aquā	–ā	aquīs	–īs	agricolā	–ā	agricolīs	–īs

Second declension (o)

The second declension is a large group of nouns consisting of mostly masculine nouns like equus, equī ("horse") and puer, puerī ("boy') and neuter nouns like castellum, castellī ("fort"). There are several small groups of feminine exceptions, including names of gemstones, trees, and some cities.

In the nominative singular, most masculine nouns consist of the stem and the affix -us, although some end in -er, which is not necessarily attached to the complete stem. Neuter nouns generally have a nominative singular consisting of the stem and the ending -um. However, every second-declension noun has the affix -ī attached as a suffix to the root of the noun in the genitive singular form. The predominant letter in the ending forms of this declension is o.

Second declension R nouns

Some masculine nouns of the second declension end in an –er or an –ir in the nominative singular. For such nouns, the genitive singular must be learned to see if the E is dropped. For example, socer, –erī keeps its E. However, the noun magister, –trī ("teacher") drops its E in the genitive singular. Nouns with –ir in the nominative singular never drop the I.

The declension of second declension R nouns is identical to that of the regular second declension, with the exception of the vocative singular, which is identical to the nominative rather than ending in an -e.

For declension tables of second declension nouns, see the Appendix:Latin second declension.

Second declension Greek nouns

The second declension contains two types of masculine Greek nouns and one form of neuter Greek noun. These nouns are irregular only in the singular, as are their first declension counterparts. Greek nouns in the second declension are derived from Omicron Declension.

Some Greek nouns may be declined as normal, Latin nouns. For example, theātron can appear as theātrum.

Peculiarities

• Nouns ending with –vus, –quus and –vum may be declined in two ways. Their alternate inflections resemble Old Latin.

	'servos, –ī slave m.		'equos, –ī horse m.		'aevom, –ī eternity, age n.
	Singular		Singular		Singular
Nominative	servos	–os	equos	–os	aevom	–om
Genitive	servī	–ī	equī	–ī	aevī	–ī
Dative	servō	–ō	equō	–ō	aevō	–ō
Accusative	servom	–om	equom	–om	aevom	–om
Vocative	serve	–e	eque	–e	aevom	–om
Ablative	servō	–ō	equō	–ō	aevō	–ō

• This is an example of a noun of the second declension in Classical Latin. Note the differences in both the Nominative and Accusative cases.

	'servus, –ī slave m.				'auxilium, –ī aid, help n.
	Singular		Plural		Singular		Plural
Nominative	servus	–us	servī	–ī	auxilium	–um	auxilia	–a
Genitive	servī	–ī	servōrum	–ōrum	auxiliī	–ī	auxiliōrum	–ōrum
Dative	servō	–ō	servīs	–īs	auxiliō	–ō	auxiliīs	–īs
Accusative	servum	–um	servōs	–ōs	auxilium	–um	auxilia	–a
Vocative	serve	–e	servī	–ī	auxilium	–um	auxilia	–a
Ablative	servō	–ō	servīs	–īs	auxiliō	–ō	auxiliīs	–īs

• The plural of deus (god, deity) is also irregular.

Nom.	dī / di
Gen.	deōrum / deum
Dat.	dīs / diis / deis
Acc.	deōs
Voc.	dī
Abl.	dīs

• The Vocative Singular of Deus is also "Deus", instead of substituting an -e for the -us (i.e. "dee") as would normally be expected for a 2nd declension -us noun.

Third declension (i)

The third declension is the largest group of nouns. These nouns may end in –a,–e, –ī, –ō, –y, –c, –l, –n, –r, –s, –t, or –x . It consists of masculine, neuter, and feminine nouns of variable nominative cases and roots. The third declension includes flumen, fluminis neut. ("river"), flos, floris masc. ("flower"), and pax, pacis fem. ("peace"). Each noun has the affix -is as a suffix attached to the root of the noun in the genitive singular form. Masculine, feminine and neuter nouns each have their own special nominative singular endings. For instance, only masculine nouns end in an –or (amor). Only feminine nouns end in an –īx (phoenīx), and only neuter nouns end in an –us (onus). As in all declensions, some nouns defy these rules.

	'prīnceps, principis leader, chief, prince m.				'phoenīx, phoenīcis phoenix, fire-bird f.				'cōnāmen, conaminis effort, struggle n.
	Singular		Plural		Singular		Plural		Singular		Plural
Nominative	prīnceps	(1)	prīncipēs	–ēs	phoenīx	(1)	phoenīcēs	–ēs	cōnāmen	(1)	cōnāmina	–a
Genitive	prīncipis	–is	prīncipum	–um	phoenīcis	–is	——		cōnāminis	–is	——
Dative	prīncipī	–ī	prīncipibus	–ibus	phoenīcī	–ī	——		cōnāminī	–ī	——
Accusative	prīncipem	–em	prīncipēs	–ēs	phoenīca	–em	——		cōnāmen	(1,2)	cōnāmina	–a
Vocative	prīnceps	(1)	prīncipēs	–ēs	phoenīx	(1)	——		cōnāmen	(1)	cōnāmina	–a
Ablative	prīncipe	–e	prīncipibus	–ibus	phoenīce	–e	——		cōnāmine	–e	——

¹ The nominative singular isn't regularly the root with a suffix appended. It may be the root; it may be identical to the genitive singular; or it may take a distinct form. The same is true of other forms that are the same as the nominative singular: the vocative singular and the neuter accusative singular.

² The nominative and accusative of neuter nouns are always identical. It should not be assumed that –en is always the appropriate ending, as it might appear above.

Third declension i-stem nouns

The third declension also has a set of nouns which are declined differently. They are called i-stems. I-stems are broken into two subcategories: pure and mixed. Pure I-stems are indicated by the parisyllabic rule or special neuter endings. Mixed I-stems are indicated by the double consonant rule.

• Masculine & Feminine
• Parisyllabic Rule: Some masculine and feminine third declension i-stem nouns have the same number of syllables in the genitive as they do in the nominative. For example: amnis, –is. The nominative ends in -is.
• Double-Consonant Rule: The rest of the masculine and feminine third declension i-stem nouns have two consonants before the –is in the genitive singular. For example: pars, partis
• Neuter
• Special Neuter Ending: Neuter third declension i-stems have no rule. However, all of them end in –al, –ar or –e. For example: animal, –ālis

Pure I-stems may exhibit peculiar endings in both singular and plural. Mixed I-stems employ normal (consonant) 3rd declension endings in the singular but I-Stem endings in the plural. Note the alternative I-stem endings indicated in parentheses.

	amnis, amnis stream, torrent m. (Pure)				pars, partis part, piece f. (Mixed)				animal, animālis animal, living being n. (Pure)
	Parisyllabic Rule				Double Consonant Rule				Special Neuter Ending
	Singular		Plural		Singular		Plural		Singular		Plural
Nominative	amnis	(1)	amnēs	–ēs	pars	(1)	partēs	–ēs	animal	(1)	animālia	–ia
Genitive	amnis	–is	amnium	–ium	partis	–is	partium	–ium	animālis	–is	animālium	–ium
Dative	amnī	–ī	amnibus	–ibus	partī	–ī	partibus	–ibus	animālī	–ī	animālibus	–ibus
Accusative	amnem	–em (-im)	amnēs	–ēs (-īs)	partem / partim	–em / -im	partēs	–ēs (-īs)	animal	(1)	animālia	–ia
Vocative	amnis	(1)	amnēs	–ēs	pars	(1)	partēs	–ēs	animal	(1)	animālia	–ia
Ablative	amne / amni	–e(-i)	amnibus	–ibus	parte	–e	partibus	–ibus	animālī	–ī	animālibus	–ibus

¹ The nominative singular isn't regularly the root with a suffix appended. It may be the root; it may be identical to the genitive singular; or it may take a distinct form. The same is true of other forms that are the same as the nominative singular: the vocative singular and the neuter accusative singular.

The rules for determining I-stems from non-I-stems and "mixed" I-stems should be thought of more as "guidelines" than "rules": even among the Romans themselves, the categorization of a 3rd declension word as an I-stem or non-I-stem was quite fluid. The result is that many words that should be I-stems according to the parasyllabic and consonant stem rules, actually aren't, such as canis or iuvenis. By the parasyllabic rule, "canis" should be a masculine I-stem and thus differ from the non-I-stems by having an extra -i- in the plural Genitive form: "canium". In reality, the plural Genitive of "canis" is "canum", the form of a non-I-stem. This fluidity even in Roman times results in much more uncertainty in medieval Latin, as scholars were trying to imitate what was fluid to begin with. The result is that some medieval Latin scribes may go so far as to "overcompensate", taking obviously non-I-stem 3rd declension words like "ars, artis" and adding extra i's i.e. "artim, arti".

Peculiarities

In the third declension, there are four irregular nouns.

Case
	vīs force, power f.		sūs, suis swine, pig, hog c.		bōs, bovis ox, bullock c.		Iuppiter, Iovis Jupiter m.
Singular	Plural	Singular	Plural	Singular	Plural	Singular
Nominative	vīs	vīrēs	sūs	suēs	bōs	bovēs	Iuppiter
Genitive	——	vīrium	suis	suum	bovis	boum	Iovis
Dative	——	vīribus	suī	subus	bovī	bōbus / bubus	Iovī
Accusative	vim	vīrēs	suem	suēs	bovem	bovēs	Iovem
Vocative	vīs	vīrēs	sūs	suēs	bōs	bovēs	Iuppiter
Ablative	vī	vīribus	sue	subus	bove	bōbus	Iove

Fourth declension (u)

The fourth declension is a group of nouns consisting of mostly masculine words like 'wave' (fluctus, fluctūs masc.) and 'port' (portus, portūs masc.) with a few feminine exceptions, including 'hand' (manus, manūs fem.). The fourth declension also includes several neuter nouns like 'knee' (genu, genūs neut.). Each noun has the affix -ūs as a suffix attached to the root of the noun in the genitive singular form. The predominant letter in the ending forms of this declension is u.

	'portus, –ūs port, haven, harbor m.				'cornū, –ūs horn, strength n.
	Singular		Plural		Singular		Plural
Nominative	portus	–us	portūs	–ūs	cornū	–ū	cornua	–ua
Genitive	portūs	–ūs	portuum	–uum	cornūs	–ūs	cornuum	–uum
Dative	portuī	–uī	portibus	–ibus	——		cornibus	–ibus
Accusative	portum	–um	portūs	–ūs	cornū	–ū	cornua	–ua
Vocative	portus	–us	portūs	–ūs	cornū	–ū	cornua	–ua
Ablative	portū	–ū	portibus	–ibus	cornū	–ū	cornibus	–ibus

In the dative and ablative plural, –ibus is sometimes replaced with –ubus. This is so for only a few nouns, such as artus, "the limbs".

The declension of domus is irregular:

	'domus, –ūs house, home f.
	Singular		Plural
Nominative	domus	–us	domūs	–ūs
Genitive	domūs	–ūs	domōrum / domuum	–ōrum / uum
Dative	domuī	–uī	domibus	–ibus
Accusative	domum	–um	domos	–os
Vocative	domus	–us	——
Ablative	domō	–ō	domibus	–ibus

Fifth declension (e)

The fifth declension is a small group of nouns consisting of mostly feminine words like 'affair, matter, thing' (rēs, reī fem.) and 'day' (diēs, diēī usually feminine, except on notable days when it is masculine). Each noun has either the affix -ēī or –eī as a suffix attached to the root of the noun in the genitive singular form.

	'effigiēs, –ēī effigy, ideal f.				'spēs, –eī hope, anticipation f.
	Singular		Plural		Singular		Plural
Nominative	effigiēs	–ēs	effigiēs	–ēs	spēs	–ēs
Genitive	effigiēī	–ēī	——		speī	–eī
Dative	effigiēī	–ēī	——		speī	–eī
Accusative	effigiem	–em	effigiēs	–ēs	spem	–em
Vocative	effigiēs	–ēs	——		spēs	–ēs
Ablative	effigiē	–ē	——		spē	–ē

Note that nouns ending in iēs have long ēī in the dative and genitive, while nouns ending in a consonant + ēs have short eī in these cases.

This declension class is the last to develop in Latin.

Pronouns

Relative and demonstrative pronouns are generally declined like first and second declension adjectives, with the following differences:

• the nominatives are often irregular
• the dative singular ends in -ī: rather than -ae or -ō.
• the genitive singular ends in -īus rather than -ae or -ī.

These differences identify the "pronominal" declension, and a few adjectives also follow this pattern.

Personal pronouns

The first and second persons are irregular. They may be only masculine or feminine.

	First Person		Second Person
	ego, meī I m. and f.	nōs, nostrum we m. and f.	tū, tuī thou m. and f.	vōs, vestrum ye m. and f.
	Singular	Plural	Singular	Plural
Nominative	ego	nōs	tū	vōs
Genitive	meī	nostrum1	tuī	vestrum1
Dative	mihi	nōbīs	tibi	vōbīs
Accusative	mē	nōs	tē	vōs
Vocative	——	——	tū	vōs
Ablative	mē	nōbīs	tē	vōbīs

¹—may be nostrī or vestrī

Usually, to show the ablative of accompaniment, cum would be added to the ablative form. Though, with personal pronouns and the interrogative (not with 3rd person), cum is added on to the end of the ablative form. For example: mēcum, nōbīscum, tēcum, vōbīscum and quōcum (sometimes quīcum).

	'is, eī he, they m.		'ea, eae she, they f.		'id, ea it, they n.
	Singular	Plural	Singular	Plural	Singular	Plural
Nominative	is	eī, iī	ea	eae	id	ea
Genitive	eius	eōrum	eius	eārum	eius	eōrum
Dative	eī	eīs, iīs	eī	eīs, iīs	eī	eīs, iīs
Accusative	eum	eōs	eam	eās	id	ea
Vocative	-	-	-	-	-	-
Ablative	eō	eīs, iīs	eā	eīs, iīs	eō	eīs, iīs

The third person reflexive pronouns always refer back to the subject whether it be singular or plural.

	—, suī himself, herself itself, oneself, themselves
Nominative	—
Genitive	suī
Dative	sibi
Accusative	sē, sēsē
Vocative	-
Ablative	sē, sēsē

Interrogative pronouns

The interrogative pronouns are used strictly for asking questions. It is best not to confuse them with the relative pronoun and the interrogative adjective (which is declined like the relative pronoun). Interrogative pronouns rarely occur in the plural, though they may. The plural interrogative pronouns are the same as the plural relative pronouns.

	'quis who? m. and f.	'quid what? n. only
	Singular
Nominative	quis	quid
Genitive	cuius	cuius
Dative	cui	cui
Accusative	quem	quid
Vocative	-	-
Ablative	quō	quō

Demonstrative pronouns and adjectives

	'hic, haec, hoc this, this one						'ille, illa, illud that, that one
	Masculine		Feminine		Neuter		Masculine		Feminine		Neuter
	Singular	Plural	Singular	Plural	Singular	Plural	Singular	Plural	Singular	Plural	Singular	Plural
Nominative	hic	hī	haec	hae	hoc	haec	ille	illī	illa	illae	illud	illa
Genitive	huius	hōrum	huius	hārum	huius	hōrum	illīus	illōrum	illīus	illārum	illīus	illōrum
Dative	huic	hīs	huic	hīs	huic	hīs	illī	illīs	illī	illīs	illī	illīs
Accusative	hunc	hōs	hanc	hās	hoc	haec	illum	illōs	illam	illās	illud	illa
Vocative	-	-	-	-	-	-	-	-	-	-	-	-
Ablative	hōc	hīs	hāc	hīs	hōc	hīs	illō	illīs	illā	illīs	illō	illīs

• Another demonstrative pronoun iste, ista, istud, which means 'that of yours', and the intensive pronoun ipse, ipsa, ipsum follow the declension of ille, illa, illud.

Relative pronouns

	'quī, quae, quod who, which, that
	Masculine		Feminine		Neuter
	Singular	Plural	Singular	Plural	Singular	Plural
Nominative	quī	quī	quae	quae	quod	quae
Genitive	cūius	quōrum	cūius	quārum	cūius	quōrum
Dative	cui	quibus	cui	quibus	cui	quibus
Accusative	quem	quōs	quam	quās	quod	quae
Vocative	-	-	-	-	-	-
Ablative	quō	quibus	quā	quibus	quō	quibus

Adjectives

First and second declension adjectives

First and second declension are inflected in the masculine, the feminine and the neuter; the masculine form typically ends in –us (although some end in -er, see below), the feminine form ends in –a, and the neuter form ends in –um. Therefore, adjectives are given like altus, alta, altum.

	'altus, –a, –um high, long, tall
	Masculine				Feminine				Neuter
	Singular		Plural		Singular		Plural		Singular		Plural
Nominative	altus	–us	altī	–ī	alta	–a	altae	–ae	altum	–um	alta	–a
Accusative	altum	–um	altōs	–ōs	altam	–am	altās	–ās	altum	–um	alta	–a
Genitive	altī	–ī	altōrum	–ōrum	altae	–ae	altārum	–ārum	altī	–ī	altōrum	–ōrum
Dative	altō	–ō	altīs	–īs	altae	–ae	altīs	–īs	altō	–ō	altīs	–īs
Vocative	alte	–e	altī	–ī	alta	–a	altae	–ae	altum	–um	alta	–a
Ablative	altō	–ō	altīs	–īs	altā	–ā	altīs	–īs	altō	–ō	altīs	–īs

First and second declension –r adjectives

Some first and second declension adjectives' masculine form end in an –er. As with second declension nouns –r nouns, some adjectives retain the e throughout inflection, and some omit it. Sacer, sacra, sacrum omits its e while miser, misera, miserum keeps it.

	'miser, –era, –erum sad, poor, unhappy
	Masculine				Feminine				Neuter
	Singular		Plural		Singular		Plural		Singular		Plural
Nominative	miser	–er	miserī	–ī	misera	–a	miserae	–ae	miserum	–um	misera	–a
Genitive	miserī	–ī	miserōrum	–ōrum	miserae	–ae	miserārum	–ārum	miserī	–ī	miserōrum	–ōrum
Dative	miserō	–ō	miserīs	–īs	miserae	–ae	miserīs	–īs	miserō	–ō	miserīs	–īs
Accusative	miserum	–um	miserōs	–ōs	miseram	–am	miserās	–ās	miserum	–um	misera	–a
Vocative	miser	–er	miserī	–ī	misera	–a	miserae	–ae	miserum	–um	misera	–a
Ablative	miserō	–ō	miserīs	–īs	miserā	–ā	miserīs	–īs	miserō	–ō	miserīs	–īs

	'sacer, –cra, –crum sacred, holy
	Masculine				Feminine				Neuter
	Singular		Plural		Singular		Plural		Singular		Plural
Nominative	sacer	–er	sacrī	–ī	sacra	–a	sacrae	–ae	sacrum	–um	sacra	–a
Genitive	sacrī	–ī	sacrōrum	–ōrum	sacrae	–ae	sacrārum	–ārum	sacrī	–ī	sacrōrum	–ōrum
Dative	sacrō	–ō	sacrīs	–īs	sacrae	–ae	sacrīs	–īs	sacrō	–ō	sacrīs	–īs
Accusative	sacrum	–um	sacrōs	–ōs	sacram	–am	sacrās	–ās	sacrum	–um	sacra	–a
Vocative	sacer	–er	sacrī	–ī	sacra	–a	sacrae	–ae	sacrum	–um	sacra	–a
Ablative	sacrō	–ō	sacrīs	–īs	sacrā	–ā	sacrīs	–īs	sacrō	–ō	sacrīs	–īs

First and second –īus genitive adjectives

There are nine first and second declension adjectives that are irregular in the genitive and the dative in all genders. They are easily remembered by using the acronym UNUS NAUTA. They are:

alius, –a, –ud; (gen. sing. alterīus to avoid aliīus); another
ūllus, –a, –um; any
uter, –tra, –trum; which (of two)
sōlus, –a, –um; sole, alone
alter, –era, –erum; the other (of two)
nūllus, –a, –um; no, none (of any)
neuter, –tra, –trum; neither (of two)
tōtus, –a, –um; whole
ūnus, –a, –um; one

	'ūllus, –a, –um any
	Masculine				Feminine				Neuter
	Singular		Plural		Singular		Plural		Singular		Plural
Nominative	ūllus	–us	ūllī	–ī	ūlla	–a	ūllae	–ae	ūllum	–um	ūlla	–a
Genitive	ūllīus	–īus	ūllōrum	–ōrum	ūllīus	–īus	ūllārum	–ārum	ūllīus	–īus	ūllōrum	–ōrum
Dative	ūllī	–ī	ūllīs	–īs	ūllī	–ī	ūllīs	–īs	ūllī	–ī	ūllīs	–īs
Accusative	ūllum	–um	ūllōs	–ōs	ūllam	–am	ūllās	–ās	ūllum	–um	ūlla	–a
Vocative	ūlle	–e	ūllī	–ī	ūlla	–a	ūllae	–ae	ūllum	–um	ūlla	–a
Ablative	ūllō	–ō	ūllīs	–īs	ūllā	–ā	ūllīs	–īs	ūllō	–ō	ūllīs	–īs

Third declension adjectives

Third declension adjectives are normally declined like third declension i-stem nouns, except for the fact they always have a –ī rather than a -e in the ablative singular (unlike i-stem nouns, in which only neuters have –ī). Some adjectives, however, like the one-ending vetus, veteris (old, aged), have an -e in the ablative singular (all genders), a -um in the genitive plural (all genders), and a -a in the nominative and accusative plural (neuter only).

Third declension adjectives with one ending

Third declension adjectives with one ending have single nominative ending for all genders. Like nouns, a genitive is given for the purpose of inflection.

	'atrōx, –ōcis terrible, mean, cruel
	Masculine & Feminine				Neuter
	Singular		Plural		Singular		Plural
Nominative	atrōx	–ōx	atrōcēs	–ēs	atrōx	–ōx	atrōcia	–ia
Genitive	atrōcis	–is	atrōcium	–ium	atrōcis	–is	atrōcium	–ium
Dative	atrōcī	–ī	atrōcibus	–ibus	atrōcī	–ī	atrōcibus	–ibus
Accusative	atrōcem	–em	atrōcēs	–ēs1	atrōx	–ōx	atrōcia	–ia
Vocative	atrōx	–ōx	atrōcēs	–ēs	atrōx	–ōx	atrōcia	–ia
Ablative	atrōcī	–ī²	atrōcibus	–ibus	atrōcī	–ī²	atrōcibus	–ibus

¹—may end in –īs
²—may end in –e

Third declension adjectives with 2 endings

Third declension adjectives that have 2 endings have one form for the masculine and feminine, and a separate form for the neuter. The ending for the masculine and feminine is –is, and the ending for the neuter is –e. Because the sexed form ends in an –is, we find the adjective genitive singular.

	'agilis, –e nimble, swift
	Masculine & Feminine				Neuter
	Singular		Plural		Singular		Plural
Nominative	agilis	–is	agilēs	–ēs	agile	–e	agilia	–ia
Genitive	agilis	–is	agilium	–ium	agilis	–is	agilium	–ium
Dative	agilī	–ī	agilibus	–ibus	agilī	–ī	agilibus	–ibus
Accusative	agilem	–em	agilēs	–ēs1	agile	–e	agilia	–ia
Vocative	agilis	–is	agilēs	–ēs	agile	–e	agilia	–ia
Ablative	agilī	–ī	agilibus	–ibus	agilī	–ī	agilibus	–ibus

¹—may end in –īs

Third declension adjectives with three endings

Third declension adjectives with three endings have three separate nominative forms for all three genders. Like third and second declension –r nouns, the masculine ends in an –er. The feminine ends in an –ris, and the neuter ends in an –re. With that information, we come upon the genitive singular needed for inflection, the feminine form.

	'celer, –eris, –ere swift, rapid, brash
	Masculine				Feminine				Neuter
	Singular		Plural		Singular		Plural		Singular		Plural
Nominative	celer	–er	celerēs	–ēs	celeris	–is	celerēs	–ēs	celere	–e	celeria	–ia
Genitive	celeris	–is	celerium	–ium	celeris	–is	celerium	–ium	celeris	–is	celerium	–ium
Dative	celerī	–ī	celeribus	–ibus	celerī	–ī	celeribus	–ibus	celerī	–ī	celeribus	–ibus
Accusative	celerem	–em	celerēs	–ēs1	celerem	–em	celerēs	–ēs1	celere	–e	celeria	–ia
Vocative	celer	–er	celerēs	–ēs	celeris	–is	celerēs	–ēs	celere	–e	celeria	–ia
Ablative	celerī	–ī	celeribus	–ibus	celerī	–ī	celeribus	–ibus	celerī	–ī	celeribus	–ibus
	'alacer, –cris, –cre lively, jovial, animated
	Masculine				Feminine				Neuter
	Singular		Plural		Singular		Plural		Singular		Plural
Nominative	alacer	–er	alacrēs	–ēs	alacris	–is	alacrēs	–ēs	alacre	–e	alacria	–ia
Genitive	alacris	–is	alacrium	–ium	alacris	–is	alacrium	–ium	alacris	–is	alacrium	–ium
Dative	alacrī	–ī	alacribus	–ibus	alacrī	–ī	alacribus	–ibus	alacrī	–ī	alacribus	–ibus
Accusative	alacrem	–em	alacrēs	–ēs1	alacrem	–em	alacrēs	–ēs1	alacre	–e	alacria	–ia
Vocative	alacer	–er	alacrēs	–ēs	alacris	–is	alacrēs	–ēs	alacre	–e	alacria	–ia
Ablative	alacrī	–ī	alacribus	–ibus	alacrī	–ī	alacribus	–ibus	alacrī	–ī	alacribus	–ibus

¹—may end in –īs

Comparison and superlative forms of adjectives

As in English, adjectives have superlative and comparative forms. For regular first and second declension and third declension nouns with one or two endings, the comparison is formed by adding an –ior for the masculine and feminine, and an –ius for the neuter to the base. The genitive for both are formed by adding an –iōris. Therefore, they are declined like the third declension. However, they are not declined as i-stems are. Superlatives formed by adding an –issimus, –a, –um to the base. Now, we find that superlatives are declined like first and second declension adjectives.

Adjective	Positive	Comparative	Superlative
	benignus, –a, –um (kind, nice)	benignior, –ius	benignissimus, –a, –um
	frīgidus, –a, –um (cold, chilly)	frīgidior, –ius	frīgidissimus, –a, –um
	calidus, –a, –um (hot, fiery)	calidior, –ius	calidissimus, –a, –um
	pugnāx, –ācis (pugnacious)	pugnācior, –ius	pugnācissimus, –a, –um
	fortis, –e (strong, robust)	fortior, –ius	fortissimus, –a, –um
	aequālis, –e (equal, even)	aequālior, –ius	aequālissimus, –a, –um

Comparisons and superlatives of –er adjectives

Adjectives (in the third and first and second declensions) that have masculine nominative singular forms ending in –er have different forms. If the feminine and neuter forms drop the E, use that for the comparative form. The superlative is formed by adding an –rimus onto the masculine form.

Adjective	Positive	Comparative	Superlative
	pulcher, –cra, –crum (pretty, beautiful)	pulchrior, –ius	pulcherrimus, –a, –um
	sacer, –cra, –crum (sacred, holy)	sacrior, –ius	sacerrimus, –a, –um
	tener, –era, –erum (delicate, tender)	tenerior, –ius	tenerrimus, –a, –um
	ācer, –cris, –cre (sharp)	ācrior, –ius	ācerrimus, –a, –um
	celēber, –bris, –bre (celebrated, famous)	celēbrior, –ius	celēberrimus, –a, –um
	celer, –eris, –ere (quick, fast)	celerior, –ius	celerrimus, –a, –um

Comparisons and superlatives of –lis adjectives

Some third declension adjectives with two endings in –lis in the sexed nominative singular have irregular superlative forms. It should be noted that the following are the only adjectives that have this unique form.

Adjective	Positive	Comparative	Superlative
	facilis, –e (easy)	facilior, –ius	facillimus, –a, –um
	difficilis, –e (hard, difficult)	difficilior, –ius	difficillimus, –a, –um
	similis, –e (similar, like)	similior, –ius	simillimus, –a, –um
	dissimilis, –e (unlike, dissimilar)	dissimilior, –ius	dissimillimus, –a, –um
	gracilis, –e (slender, slim)	gracilior, –ius	gracillimus, –a, –um
	humilis, –e (low, humble)	humilior, –ius	humillimus, –a, –um

Irregular comparisons and superlatives

As in most languages, Latin has adjectives that have irregular comparisons and superlatives.

Adjective	Positive	Comparative	Superlative
	bonus, –a, –um (good)	melior, –ius	optimus, –a, –um
	malus, –a, –um (bad, evil)	peior, –ius	pessimus, –a, –um
	magnus, –a, –um (great, large)	maior, –ius	maximus, –a, –um
	parvus, –a, –um (small, slight)	minor, –us	minimus, –a, –um
	multus, –a, –um (much, many)	plūs1	plurimus, –a, –um
	maturus, –a, –um (ripe, mature)	maturior, –ius	maturrimus, –a, –um2
	nēquam3 (worthless)	nēquior, –ius	nēquissimus, –a, –um
	posterus, –a, –um (next, future)	posterior, –ius	postremus, –a, –um
	superus, –a, –um (above, upper)	superior, –ius	supremus, –a, –um
	exterus, –a, –um (outer, outward)	exterior, –ius	extremus, –a, –um
	novus, –a, –um (new, strange)	recentior, –ius	novissimus, –a, –um
	senex, senis (old, aged)	senior, –ius	——
	iuvenis, –is (young, youthful)	iunior, –ius	——

• 1: noun used with genitive to express more of something
• 2: often replaced by the regular form 'maturissimus, –a, –um'
• 3: indeclinable

Declension of īdem

The adjective īdem, eadem, idem means 'same.' It is a variant of the third person pronouns which were declined earlier. Generally, they are formed by adding –dem to a declined third person pronouns. However, some forms have been changed to ease pronunciation.

	'īdem, eadem, idem the same, same as
	Masculine		Feminine		Neuter
	Singular	Plural	Singular	Plural	Singular	Plural
Nominative	īdem	eīdem, iīdem	eadem	eaedem	idem	eadem
Genitive	eiusdem	eōrundem	eiusdem	eārundem	eiusdem	eōrundem
Dative	eīdem	eīsdem, iīsdem	eīdem	eīsdem, iīsdem	eīdem	eīsdem, iīsdem
Accusative	eundem	eōsdem	eandem	eāsdem	idem	eadem
Vocative	īdem	eīdem, iīdem	eadem	eaedem	idem	eadem
Ablative	eōdem	eīsdem, iīsdem	eādem	eīsdem, iīsdem	eōdem	eīsdem, iīsdem

Declension of numerals

See also: Roman numerals for symbology.

There are several different kinds of numeral words in Latin: the two most common are Cardinal numerals, and Ordinal numerals. There are also several more rare numerals such as Distributive numerals and Adverbial numerals

Cardinal numerals

All numerals, except ūnum (one), duo (two), tria (three), mīlia (thousand, sing. mīlle) and ducentī (two-hundred) are indeclinable adjectives. Ūnus, ūna, ūnum is declined like a first and second declension adjective with an –īus in the genitive, and –ī in the dative. Duo is declined irregularly and tria is declined like a third declension adjective.

	duo, duae, duo two
	Masculine	Feminine	Neuter
	Plural
Nominative	duo	duae	duo
Genitive	duōrum / duum	duārum	duōrum
Dative	duōbus	duābus	duōbus
Accusative	duōs / duo	duās	duo
Vocative	duo	duae	duo
Ablative	duōbus	duābus	duōbus

It should be noted that ambō, "both", is declined as duo is, though its o is long.

	trēs, tria
	Masculine & Feminine	Neuter'''
	Plural
Nominative	trēs	tria
Genitive	trium	trium
Dative	tribus	tribus
Accusative	trēs, trīs	tria
Vocative	trēs	tria
Ablative	tribus	tribus

The word mīlle, is singular, an adjective and indeclinable. However, its irregular plural, mīlia, is a plural noun and is used in the same way plūs is.

	mīlia, mīlium (a) thousand n.
	Plural
Nominative	mīlia
Genitive	mīlium
Dative	mīlibus
Accusative	mīlia
Vocative	mīlia
Ablative	mīlibus

• Note that to write the phrase "four thousand horses" in Latin, the genitive is used: "quattuor milia equōrum", literally, "four thousands of horses".

As stated before, the rest of the numbers are indeclinable adjectives. They are also indeclinable as substantives.

1	I	ūnus, –a, –um	11	XI	ūndecim	21	XXI	ūnus et vigintī	101	CI	centum et ūnus
2	II	duo, –ae, –o	12	XII	duodecim	22	XXII	duō et vigintī	200	CC	ducentī, –ae, –a
3	III	trēs, –ia	13	XIII	trēdecim	30	XXX	trīgintā	300	CCC	trecentī
4	IV	quattuor	14	XIV	quattuordecim	40	XL	quadrāgintā	400	CD	quadrigentī
5	V	quīnque	15	XV	quīndecim	50	L	quīnquāgintā	500	D	quīngentī
6	VI	sex	16	XVI	sēdecim	60	LX	sexāgintā	600	DC	sescentī
7	VII	septem	17	XVII	septendecim	70	LXX	septuāgintā	700	DCC	septingentī
8	VIII	octō	18	XVIII	duodēvigintī	80	LXXX	octōgintā	800	DCCC	octingentī
9	IX	novem	19	XIX	ūndēvigintī	90	XC	nōnāgintā	900	CM	nōngentī
10	X	decem	20	XX	vigintī	100	C	centum	1000	M	mīlle

Ordinal numerals

Ordinal numerals all decline like normal 1st and 2nd declension adjectives.

• Primus = first
• Secundus = second
• Tertius = third
• Vicensimus = twentieth

Note: "Secundus" only means "second" in the sense of "following". The adjective Alter, -ra, -rum meaning "the other (of two)" was more frequently used in many instances that English would use "second".

Ordinal numbers, not Cardinal numbers, are commonly used to represent dates, because they are in the format of "in the tenth year of Caesar", etc. which also carried over into the Anno Domini system and Christian dating, i.e. "anno post Christum nato centensimo" = AD 100.

Distributive numerals

A rare numeral construction denoting an equal number distributed among several objects, i.e. "how many each?" "two by two". They decline like normal 1st and 2nd declension adjectives, and are logically always plural. Bis, Bina = "twice two". A classical example would be "Uxores habent deni duo deniqui inter se communes" = "groups of ten or twelve men had wives in common" --Gallic Wars, Julius Caesar

Adverbial numerals

Adverbial numerals are (as the name states) indeclinable adverbs, but because all of the other numeral constructions are adjectives they are listed here with them. Adverbial numerals give how many times a thing happened. Semel = once, Bis = twice, Ter = thrice (three times), Quater = four times, etc

Adverbs and their comparisons and superlatives

Adverbs are not declined. However, adverbs must be formed if one wants to make an adjective into an adverb.

First and second declension adjectives' adverbs

First and second declension adjectives' adverbs are formed by adding an –ē onto their bases.

Adjective	Adverb
clārus, –a, –um (clear, famous)	clārē (clearly, famously)
validus, –a, –um (strong, robust)	validē (strongly, robustly)
īnfīrmus, –a, –um (weak)	īnfīrmē (weakly)
solidus, –a, –um (complete, firm)	solidē (completely, firmly)
integer, –gra, –grum (whole, fresh)	integrē (wholly, freshly)
līber, –era, –erum (free)	līberē (freely)

Third declension adjectives' adverbs

Typically, third declension adjectives' adverbs are formed by adding an –iter onto their bases. However, most third declension adjectives with one ending simply add an –er to their bases.

Adjective	Adverb
prūdēns, –entis (prudent)	prūdenter (prudently)
audāx, –ācis (bold)	audācter (boldly)
virilis, –e (courageous, spirited)	viriliter (courageously, spiritedly)
salūbris, -e (wholesome)	salūbriter (wholesomely)

Adverbs' comparative and superlative forms

Adverbs' comparative forms are their neuter adjectives' comparative forms. Adverbs' superlative forms are made in the same way in which first and second declension adjectives' adverbs are made.

First and second declension adjectives' adverbs are formed by adding an –ē onto their bases.

Positive	Comparative	Superlative
clārē (clearly, famously)	clārius	clārissimē
solidē (completely, firmly)	solidius	——
līberē (freely)	līberius	——
prudenter (prudently)	prudentius	prudentissimē
salūbriter (wholesomely)	salūberius	salūberissimē

Irregular adverbs and their comparative and superlative forms

As so with adjectives, there are irregular adverbs with peculiar comparative and superlative forms.

Positive	Comparative	Superlative
bene (well)	melius	optimē
male (ill, badly)	peius	pessimē
māgnoperē (greatly)	magis	maximē
multum (much, a lot)	plūs	plūrimum
parvum (little)	minus	minimē
nēquiter (worthlessly)	nēquius	nēquissimē
saepe (often)	saepius	saepissimē
mātūrē (seasonably, betimes)	mātūrius	māturrimē
prope (near)	propius	proximē
nūper (recently)	——	nūperrimē
potis (possible)	potius (rather)	potissimē (especially)
——	prius (before, previously)	prīmum /primo (first)
secus (otherwise)	sētius / sequius (less)	——

Peculiarities within declension

Irregularity in number

Some nouns are declined in the singular only. This is the case with:

• Materials such as aurum (gold) and aes (copper)
• Abstract nouns such as celeritās (speed) and scientia (knowledge)
• Proper names such as Iulius (Julius) and Clāra (Clara)

There are nouns that are declined only in the plural as well (plurale tantum):

• Many festivals, such as Saturnalia
• Words like castra (camp) and arma (arms)
• A few geographical names are plural such as Thēbae (Thebes).

Indeclinable nouns

Indeclinable nouns are neuter nouns which occur only in the nominative and the accusative singular. There are only six such nouns:

• fās — fate, divine law
• īnstar — likeness
• māne — morning
• nefās — sin, abomination
• nihil / nil — nothing, none
• secus — sex, coitus

Heterogeneous nouns

Heterogeneous nouns are nouns which vary in respect to gender.

• A few nouns in the second declension occur in both the neuter and masculine. However, their meanings remain the same.
• Some nouns are one gender in the singular, but become another gender in the plural. They may also change in meaning.

Singular	Plural
balneum n. bath	balneae f. or balnea n. bath-house
epulum n. feast, banquet	epulae f. feasts, banquets
frēnum n. bridle, curb	frēnī m. bridle, curb
iocus m. joke, jest	ioca n. or ioci m. jokes, jests
locus m. place, location	loca n. places, locations; locī region
rāstrum n. hoe, rake	rāstrī m. hoes, rakes

Plurals with alternative meanings

The nouns below have a specific singular meaning, yet have a different plural meaning.

Singular	Plural
aedēs, –is f. building, temple	aedēs, –ium rooms, house
auxilium, –ī n. help, aid	auxilia, –ōrum auxiliary troops
carcer, –eris m. prison, cell	carcerēs, –um starting-place of a chariot race
castrum, –ī n. fort, castle, fortress	castra, –ōrum milit. camp, encampment
cōpia, –ae f. plenty, much, abundance	cōpiae, –ārum troops
fīnis, –is m. end, boundary	fīnēs, –ium territory
fortūna, –ae f. luck, chance	fortūnae –ārum wealth
grātia, –ae f. charm, favor	grātiae, –ārum thanks
impedīmentum, –ī m. impediment, hindrance	impedīmenta, –ōrum baggage
littera, –ae f. letter (as in A, B, C, etc.)	litterae, –ārum epistle, scholarship, literature
mōs, mōris m. habit, inclination	mōrēs, –um m. morals, character
opera, –ae f. trouble, pains	operae, –ārum workmen
opis (gen.; nom. and dat. do not occur) f. the goddess Ops (pers.), help	opēs, –ium resources, wealth
pars, partis f. part, piece	partēs, –ium office, function
sāl, salis m. salt, sea water	salēs, –um wit, smarts

Notes

1. The archaism aquai occurs frequently in Virgil, Cicero, Lucretius and others, to evoke the style of older writers.
2. Being a Greek word, the accusative form is phoenica (Ovid, Metamorphoses 15.393 ).

References

• New Latin Grammar, an eBook, originally written by Charles Edwin Bennett at the Project Gutenberg
• Latin grammar - interactive

See also

• Latin conjugation
• William Whitaker's Words
• Latin mnemonics