List of words that may be spelled with a ligature

This list of words that may be spelled with a ligature in English encompasses words which have letters that may, in modern usage, either be rendered as two distinct letters or as a single, combined letter. This includes AE being rendered as Æ (an æsc or ash) and OE being rendered as Œ (an œthel). Note that when a c is before a ligature, it makes the sound /s/ rather than /k/ as might be expected (because c makes the sound /k/ before an a or o in English).

The use of the œ and æ is obsolescent in modern English, and has been used predominantly in British English. It is usually used to evoke archaism, or in literal quotations of historic sources.

The fl and fi ligatures, among others, are still commonly used to render modern text in fine typography. Programs such as QuarkXpress and Adobe InDesign can be configured to automatically replace the individual characters with the appropriate ligatures.


Note that some words contain an ae which may not be written æ because the etymology is not from the Greek -αι- or Latin -ae- diphthongs. These include:

  • In instances of aer (starting or within a word) when it makes the sound IPA [ɛə]/[eə] (air). Comes from the Latin āër, Greek ἀήρ.
  • When ae makes the diphthong sound IPA .
  • When ae is found in a foreign phrase or loan word and it is unacceptable to use the ligature in that language. For example, when in a German loan word or phrase, if the a with an umlaut (ä) is written as ae, it is incorrect to write it with the ligature.

Common form Ligature form Other forms Etymology
aeciospore æciospore combination of New Latin aecium and New Latin spora→spore (acium+spore)
aecidium æcidium (aecium) New Latin aecidium, from Greek αἰκία (aikia)
aecium æcium (aecidium) New Latin aecidium, from Greek αἰκία (aikia)
aedicule ædicule edicule (AmE) Latin aediculum
Aegis Ægis Egis (AmE) Latin from Greek Αἰγίς (Aigis)
Aeolian Æolian Eolian (AmE) Latin Aeolis from Greek mythology Αἰολίς (Aiolis)
Aeolis Æolis Latin Aeolis, from Greek Αἰολίς (Aiolis)
aeon æon eon (AmE) Late Latin aeon, from Greek αἰών (aion).
aerose Ærose Latin aerosus, from Greek αης (aes)
aerugite ærugite (aerugo) Latin aerugo, from Greek αης (aes)
aerugo ærugo (aerugite) Latin aerugo, from Greek αης (aes)
aeschynite æschynite eschynite (AmE) Greek αἰσχύνω (aischuno)
aesculin æsculin esculin (AmE)
aesculetin æsculetin esculetin (AmE)
aesthetic æsthetic esthetic (AmE)
aestival æstival estival (AmE)
aestivation æstivation estivation (AmE) Latin aestivare, from aestivus, from aestas
Aether Æther ether (AmE) Latin aether, from Greek αἰθήρ (aither)
aethereal æthereal or ætherial ethereal (AmE), etherial (AmE - rare), aetherial (BrE - rare)
Aethrioscope Æthrioscope Ethrioscope Greek αἴθριον (aithrion)
aetiology ætiology etiology (AmE)
algae algæ algas (very rare)
ambilevous ambilævous From Latin ambilaevus (ambi- (“both”) + laevus (“left”)), a calque of Ancient Greek ἀμφαρίστερος (ampharisteros).
anaemia anæmia anemia (AmE)
anaesthesia anæsthesia anesthesia (BrE)
antennae antennæ antennas
archaeology archæology archeology (AmE)
Athenaeum Athenæum Atheneum (AmE)
azotaemia azotæmia azotemia (AmE)
bacteraemia bacteræmia bacteremia (AmE)
Caesar Cæsar Cesar (AmE – rare)
caesium cæsium cesium (AmE)
chaetophorous chætophorous chetophorous
curriculum vitae curriculum vitæ Latin meaning ‘course of life’, vitæ
daedal dædal dedal
daemon dæmon demon (AmE) Greek: δαιμων (daimon)
Egypt Ægypt Aegypt (Archaic) From the Latinised Ægyptus
encyclopaedia encyclopædia encyclopedia (AmE)
era æra aera (BrE - rare) Late Latin aera, probably from Latin æs (plural æra)
et cetera et cætera et caetera, etc., &c. Latin phrase
Ethiopia Æthiopia Aethiopia
Eudaemonic eudæmonic eudemonic
faeces fæces feces (AmE)
fairy færie faerie
formulae formulæ formulas
fraenum frænum Frenum
Gaea Gæa Gaia
haemoglobin hæmoglobin hemoglobin (AmE)
haemolysis hæmolysis hemolysis (AmE)
haemophilia hæmophilia hemophilia (AmE)
haemorrhage hæmorrhage hemorrhage (AmE)
haemorrhoid hæmorrhoid hemorrhoid (AmE)
hyena hyæna hyaena
hypaethral hypæthral hypethral
ischaemia ischæmia ischemia (AmE)
judaeo judæo judeo
Judaeophobe judæophobe judeophobe (AmE)
leukaemia leukæmia leukemia (AmE)
medieval mediæval mediaeval (BrE – rare)
nebulae nebulæ nebulas plural – New LatinLatin ("mist"); akin to Old High German nebul ("fog") → Greek nephelē, nephos ("cloud")
nymphae nymphæ nymphs
nymphaea nymphæa
orthopaedic orthopædic orthopedic (AmE)
paean pæan pean (AmE)
paeon pæon
pedagogue pædagogue or pædagog pedagog (AmE), (paedagogue and paedagog exist but are both somewhat archaic)
pederasty pæderasty paederasty
paediatrics pædiatrics pediatrics (AmE)
paediatrician pædiatrician pediatrician (AmE)
paediatrist pædiatrist pediatrist (AmE)
paedophile pædophile pedophile (AmE)
palaeobotany palæobotany paleobotany (AmE)
palaeocene palæocene paleocene (AmE)
palaeoclimatology palæoclimatology paleoclimatology (AmE)
palaeography palæography palaeography (AmE)
palaeolithic palæolithic paleolithic (AmE)
palaeography palæography paleography (AmE)
palaeontology palæontology paleontology (AmE)
palaeozoic palæozoic paleozoic (AmE)
Panacaea Panacæa Panacea (AmE)
Pangaea Pangæa Pangea (AmE)
personae personæ personas
premium præmium praemium
primeval primæval primaeval (BrE - rare)
Quaestor Quæstor
Rhaetia Rhætia
septicaemia septicæmia septicemia (AmE)
scarabaeid scarabæid
scarabaeoid scarabæoid
synaesthesia synæsthesia synesthesia (AmE)
toxaemia toxæmia toxemia (AmE)
uraemia uræmia uremia (AmE)
viraemia viræmia viremia (AmE)


Common form Ligature form Other forms Etymology
amenorrhoea amenorrhœa amenorrhea (AmE) From Greek α (a) + μένόρροια (mēnorroia)
amoeba amœba ameba (AmE—rare) New Latin amoeba, from Greek ἀμοιβή (amoibē)
apnea apnœa apnoea (BrE) New Latin apnoea, from Greek απνοια (apnoia)
coeliac cœliac celiac (AmE) Latin coeliacus, from Greek κοιλιακος (koiliakos)
diarrhea diarrhœa diarrhoea (BrE) Middle English diaria, from Late Latin diarrhoea, from Greek διάρροια (diarroia)
ecology œcology oecology
economy œconomy oeconomy
ecumenism œcumenism oecumenism, rarely ocumenism
esophagus œsophagus oesophagus (BrE)
estrogen œstrogen oestrogen (BrE)
estrus œstrus oestrus
federal fœderal foederal – archaic; thus virtually never found Latin foedus
fetid fœtid foetid (BrE) Latin fētidus
fetor fœtor foetor (BrE) Middle English fetoure, from Latin fētor
fetus fœtus foetus (BrE) Middle English fetus, from Latin fētus
gonorrhoea gonorrhœa gonorrhea (AmE) Greek γονόρροια (gonorrhoia)
homeomorphism homœomorphism homoeomorphism (BrE) From Greek ὅμοιος (homoios) + μορφος (morphos)
homeopath homœopath homoeopath (BrE) From Greek ὅμοιος (homoios) + πάθος (pathos)
homeostasis homœostasis homoeostasis (BrE) From Greek ὅμοιος (homoios) + στάσις (stasis)
homoeozoic homœozoic homeozoic (AmE—rare) From Greek ὅμοιος (homoios) + ζωικός (zōikos)
hors d'oeuvre hors d'œuvre French hors d'œuvre
logorrhoea logorrhœa logorrhea (AmE) From Greek
maneuver manœuvre manoeuvre (BrE) French manœuvre, from Old French maneuvre, from Medieval Latin manuopera, from Latin manū operārī
Economics œconomics oeconomics
oedema œdema edema (AmE)
Oedipus Œdipus Oidipus (rare), Ødipus Greek Οἰδίπους (Oidipous)
oeillade œillade
oenology œnology enology (AmE) From Greek οίνος (oinos) + λόγος (logos)
oenomel œnomel
oenothera œnothera
oeuvre œuvre French œuvre, from Old French uevre, from Latin opera
onomatopoeia onomatopœia
penology pœnology
phoenix phœnix phenix (rare)
subpoena subpœna subpena (rare)
tragedy tragœdy tragoedy


  1. The variants that change '-æ' or '­-œ' to '-s' are not variants in spelling, but the same meaning of the word with a different way of forming plurals.
  2. "caesium" (see article) is preferred by the IUPAC.

Also, ligatures may be used in personal names as well, ie. Maecenus as Mæcenus, or Timothy as Timothæ, etc.

See also

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