"class, sort, variety," from Old English gecynd "kind, nature, race," related to cynn "family" (see kin), from Proto-Germanic *gakundjaz "family, race" (see kind (adj.)). Ælfric's rendition of "the Book of Genesis" into Old English came out gecyndboc. The prefix disappeared 1150-1250. No exact cognates beyond English, but it corresponds to adjective endings such as Goth -kunds, Old High German -kund. Also in English as a suffix (mankind, etc.). Other earlier, now obsolete, senses in English included "character, quality derived from birth" and "manner or way natural or proper to anyone." Use in phrase a kind of (1590s) led to colloquial extension as adverb (1804) in phrases such as kind of stupid ("a kind of stupid (person)").