C17: from Latin cognātus, from co- same + gnātus born, variant of nātus, past participle of nāscī to be born
Word Origin and History for cognate
adj.
1640s, from Latin cognatus "of common descent," from com- "together" (see co-) + gnatus, past participle of gnasci, older form of nasci "to be born" (see genus). Words that are cognates are cousins, not siblings. As a noun, from 1754.