gearyoudaoicibaDictYouDict[gear 词源字典]
gear: [13] The etymological meaning of gear is roughly ‘that which puts one in a state of readiness’ – hence ‘equipment, apparatus’. Its ultimate source is prehistoric Indo-European *garw-, which also produced the now obsolete English adjective yare ‘ready’ and (via Germanic, Italian, and French) garh [16]. A derivative *garwīn- passed into Old Norse as gervi, which English borrowed as gear. The mechanical sense of the word developed in the 16th century.
=> garb[gear etymology, gear origin, 英语词源]
gear (n.)youdaoicibaDictYouDict
c. 1200, "fighting equipment, armor and weapons," probably from Old Norse gørvi (plural gørvar) "apparel, gear," related to görr, gørr, gerr "skilled, accomplished; ready, willing," and to gøra, gørva "to make, construct, build; set in order, prepare," a very frequent verb in Old Norse, used in a wide range of situations from writing a book to dressing meat. This is from Proto-Germanic *garwjan "to make, prepare, equip" (cognates: Old English gearwe "clothing, equipment, ornament," which may be the source of some uses; Old Saxon garwei; Dutch gaar "done, dressed;" Old High German garo "ready, prepared, complete," garawi "clothing, dress," garawen "to make ready;" German gerben "to tan").

From early 14c. as "wearing apparel, clothes, dress;" also "harness of a draught animal; equipment of a riding horse." From late 14c. as "equipment generally; tools, utensils," especially the necessary equipment for a certain activity, as the rigging of a sailing ship. Meaning "toothed wheel in machinery" first attested 1520s; specific mechanical sense of "parts by which a motor communicates motion" is from 1814; specifically of a vehicle (bicycle, automobile, etc.) by 1888. Slang for "male sex organs" from 1670s.
gear (v.)youdaoicibaDictYouDict
c. 1200, "to equip oneself for fighting; to dress," probably from gear (n.) or from the verb in Old Norse. Mechanical meaning "put (machinery) in gear" is from 1851. Related: Geared; gearing.
gear (adj.)youdaoicibaDictYouDict
"stylish, excellent," British slang, 1951 (popularized c. 1963 by the Beatles), said to be from earlier that's the gear, an expression of approval (1925), from gear (n.).