Cognates

In linguistics, cognates are words that have a common etymological origin. In etymology, the cognate category excludes doublets and loanwords. The word cognate derives from the Latin noun , which means "blood relative".

Cognates do not need to have the same meaning, which may have changed as the languages developed separately. For example, consider English and Dutch or German ("to die"); these three words all derive from the same Proto-Germanic root, ("die"). English and German ("table"), with their flat surfaces, both come from Latin , but it would be a mistake to identify their later meanings as the same. Discus is from Greek δίσκος (from the verb δικεῖν "to throw"). A later and separate English reflex of discus, probably through medieval Latin desca, is (see OED s.v. desk).

Cognates also do not need to have obviously similar forms, e.g. English , French , and Armenian (hayr) all descend directly from Proto-Indo-European (PIE) *ph₂tḗr.

Examples of cognates in Indo-European languages are the words night (English), nuit (French), noche (Spanish), Nacht (German), nacht (Dutch), nag (Afrikaans), nicht (Scots), natt (Swedish, Norwegian), nat (Danish), nátt (Faroese), nótt (Icelandic), noc (Czech, Slovak, Polish), ночь, noch (Russian), ноќ, noć (Macedonian), нощ, nosht (Bulgarian), ніч, nich (Ukrainian), ноч, noch/noč (Belarusian), noč (Slovene), noć (Bosnian, Serbian, Croatian), νύξ, nyx (Ancient Greek, νύχτα/nychta in Modern Greek), nox/nocte (Latin), nakt- (Sanskrit), natë (Albanian), nos (Welsh), nueche (Asturian), noite (Portuguese and Galician), notte (Italian), nit (Catalan), nuèch/nuèit (Occitan), noapte (Romanian), nakts (Latvian), naktis (Lithuanian) and Naach (Colognian), all meaning "night" and derived from the PIE , "night".

...
Wikipedia