Английский Этимологический словарь - kind (n.)

- "class, sort, variety," from O.E. gecynd "kind, nature, race," related to cynn "family" (see kin), from P.Gmc. *gakundiz. Жlfric's rendition of "the Book of Genesis" into O.E. came out gecyndboc. Also as a suffix (mankind, etc.); use in phrase a kind of led to colloquial extension as adv. in phrases such as kind of stupid.