kindyoudaoicibaDictYouDict[kind 词源字典]
kind: [OE] Kind the noun and kind the adjective are ultimately the same word, but they split apart in pre-historic times. Their common source was Germanic *kunjam, the ancestor of English kin. From it, using the collective prefix *ga- and the abstract suffix *-diz, was derived the noun *gakundiz, which passed into Old English as gecynde ‘birth, origin, nature, race’.

The prefix ge- disappeared in the early Middle English period. Germanic *gakundiz formed the basis of an adjective, *gakundjaz, which in Old English converged with its source to produce gecynde. It meant ‘natural, innate’, but gradually progressed via ‘of noble birth’ and ‘well-disposed by nature’ to (in the 14th century) ‘benign, compassionate’ (a semantic development remarkably similar to that of the distantly related gentle).
=> kin[kind etymology, kind origin, 英语词源]
kind (n.)youdaoicibaDictYouDict
"class, sort, variety," from Old English gecynd "kind, nature, race," related to cynn "family" (see kin), from Proto-Germanic *kundjaz "family, race," from PIE *gene- "to give birth, beget" (see genus). 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)").
kind (adj.)youdaoicibaDictYouDict
"friendly, deliberately doing good to others," from Old English gecynde "natural, native, innate," originally "with the feeling of relatives for each other," from Proto-Germanic *kundi- "natural, native," from *kunjam "family" (see kin), with collective prefix *ga- and abstract suffix *-iz. Sense development from "with natural feelings," to "well-disposed" (c. 1300), "benign, compassionate" (c. 1300).