quickyoudaoicibaDictYouDict[quick 词源字典]
quick: [OE] Originally quick meant ‘alive’ (as in the now fossilized phrase the quick and the dead); it was not until the 13th century that the sense ‘rapid’ began to emerge. It goes back to a prehistoric Germanic *kwikwaz (which also produced Swedish kvick ‘rapid’); and this was descended from an Indo-European base *gwej-, which branched out into Latin vīvus ‘alive’ (source of English vivid), Greek bíos ‘life’ (source of English biology), Welsh byw ‘alive’, Russian zhivoj ‘alive’, etc.

The couch of couch grass [16] is a variant of the now seldom encountered quitch, whose Old English ancestor cwice may be related to quick (the allusion presumably being to its vigorous growth).

=> biology, vivid[quick etymology, quick origin, 英语词源]
quick (adj.)youdaoicibaDictYouDict
Old English cwic "living, alive, animate," and figuratively, of mental qualities, "rapid, ready," from Proto-Germanic *kwikwaz (cognates: Old Saxon and Old Frisian quik, Old Norse kvikr "living, alive," Dutch kwik "lively, bright, sprightly," Old High German quec "lively," German keck "bold"), from PIE root *gweie- (1) "to live" (see bio-). Sense of "lively, swift" developed by late 12c., on notion of "full of life."
NE swift or the now more common fast may apply to rapid motion of any duration, while in quick (in accordance with its original sense of 'live, lively') there is a notion of 'sudden' or 'soon over.' We speak of a fast horse or runner in a race, a quick starter but not a quick horse. A somewhat similar feeling may distinguish NHG schnell and rasch or it may be more a matter of local preference. [Buck]
Of persons, "mentally active," from late 15c. Also in Middle English used of soft soils, gravel pits, etc. where the ground is shifting and yielding (mid-14c., compare quicksand). As an adverb from c. 1300. To be quick about something is from 1937. Quick buck is from 1946, American English. Quick-change artist (1886) originally was an actor expert in playing different roles in the same performance of a show. Quick-witted is from 1520s.
quick (n.)youdaoicibaDictYouDict
"living persons," Old English cwic, from quick (adj.); frequently paired with the dead, as in Old English cwicum & deadum. The quick "tender part of the flesh" (under a nail, etc.) is from 1520s, as is the figurative use of it.