A cognate of a word is a word in another language which is derived from the same root.

As an example, the English word mother has cognates in several other Indo-European languages: Greek μητηρ (meter), Russian мать (mat'), German mutter, Sanskrit matri, and Irish mathair. These words all share a similar sound, and thousands of years ago they were all the same word in the same language.

Cognate given names also exist. For example Andrew, André, Andrea, Andrey, Andrzej and Ondrej are all cognates derived from the Greek root name Ανδρεας (Andreas).