are words that have a common origin. They may occur within a language, such as shirt
as two English words descended from the Proto-Indo-European
, meaning "to cut". They may also occur across languages, e.g. night
and German Nacht
as descendants of Proto-Indo-European , "night".
The word cognate derives from Latin cognatus, from co (with) +gnatus, natus, past participle of nasci "to be born". Literally it means "related by blood, having a common ancestor, or related by an analogous nature, character, or function".
The term cognate is not normally used with loanwords. For example, linguists would not say that the English word sushi is cognate to the Japanese word sushi, because the word was borrowed from Japanese into English.
Characteristics of cognate words
Cognates need not have the same meaning: dish
) and Tisch
), or starve
) and sterben
), or head
) and chef
("chief, head", French
), serve as examples as to how cognate terms may diverge in meaning
as languages develop separately, eventually becoming false friends
In addition to having separate meanings, cognates through processes of linguistic change may no longer resemble each other phonetically: cow and beef both derive from the same Indo-European root *gou-, cow having developed through the Germanic language family while beef has arrived in English from the Italo-Romance family descent. (ModE cow < ME cou < OE cū < PIE *gou > Latin bov- (stem; dictionary form is bos, borrowed from some Osco-Umbrian dialect) > OFr boef > ME beef)
Cognates across languages
Examples of cognates in Indo-European languages
are the words night
), ночь, noch
), νύξ, nyx
), and naktis
), all meaning "night" and derived from the Proto-Indo-European
) , "night".
Another Indo-European example is star (English), str- (Sanskrit), astre or étoile (French), αστήρ (astēr) (Greek), stella (Latin, Italian), stea (Romanian and Venetian), stairno (Gothic), astl (Armenian), Stern (German), ster (Dutch and Afrikaans), starn (Scots), stjerne (Norwegian and Danish), stjarna (Icelandic), stjärna (Swedish), setare (Persian), stoorei (Pashto), seren (Welsh), steren (Cornish), estel (Catalan), estrella (Spanish), estrela (Portuguese and Galician) and estêre (Kurdish), from the PIE , "star".
The Hebrew shalom, the Arabic salaam and the Amharic selam ("peace") are also cognates, derived from Proto-Semitic Appendix:Proto-Semitic *šalām-.
Cognates may often be less easily recognised than the above examples and authorities sometimes differ in their interpretations of the evidence. The English word milk is clearly a cognate of German Milch. On the other hand, French lait and Spanish leche (both meaning "milk") are less obviously cognates of Greek galaktos (genitive form of gala, milk) (<*g(a)lag-, galakt-), but on the other hand the Spanish adjective forms "lácteo" or "láctico" better prove this common origin, through the Latin "lactis", as well as the English word lactic (and many many other English words derived or borrowed from Latin, directly or through other Romance languages).
Cognates within the same language
Cognates can exist within the same language. For example, English ward
(*wer-, "to perceive, watch out for") are cognate as are shirt and skirt (*sker-, "to cut"). In some cases, such as "shirt" and "skirt", one of the cognate pairs has an ultimate source in another language related to English, while the other one is native, as happened with many loanwords from Old Norse (which was mutually intelligible with Old English) borrowed when the Vikings conquered part of England. Sometimes, both cognates come from other languages, often the same one but at different times. For example, the word chief comes from the Middle French chef, and its modern pronunciation preserves the Middle French consonant sound. The word chef was borrowed from the same source centuries later, by which time the consonant had changed to a "sh"-sound in French. Such words are said to be etymological twins.
False cognates are words that are commonly thought to be related (have a common origin) whereas linguistic examination reveals they are unrelated. Thus, for example, on the basis of superficial similarities one might suppose that the Latin verb habere and German haben, both meaning 'to have', are cognates. However, an understanding of the way words in the two languages evolve from Proto-Indo-European (PIE) roots shows that they cannot be cognate (see for example Grimm's law). German haben (like English have) in fact comes from PIE *kap, 'to grasp', and its real cognate in Latin is capere, 'to seize, grasp, capture'. Latin habere, on the other hand, is from PIE *gʰabʰ, 'to give, to receive', and hence cognate with English give and German geben.
The similarity of words between languages is not enough to demonstrate that the words are related to each other, in much the same way that facial resemblance does not imply a close genetic relationship between people. Over the course of hundreds and thousands of years, words may change their sound completely. Thus, for example, English five and Sanskrit pança are cognates, while English over and Hebrew a'var are not, and neither are English dog and Mbabaram dog.
Contrast this with false friends, which frequently are cognate.
In a parliamentary sense, a cognate debate means that two or more bills can be debated together, if the House does not object to the matter. Bills are only debated cognately if they are closely related.
In Mechanical Systems, the term "cognate" has been used by Hartenburg and Denavit to describe a linkage, of different geometry, which generates the same coupler curve.
Molecular Biology term
In molecular biology a ligand may have a cognate receptor. This is a receptor that specifically binds to that ligand.