flightyoudaoicibaDictYouDict[flight 词源字典]
flight: [OE] English has two distinct, etymologically unrelated words flight. One, ‘flying’, comes from a prehistoric West Germanic *flukhtiz, a derivative of the same base as produced fly (the sense ‘series of stairs’, which developed in the 18th century, was perhaps modelled on French volée d’escalier, literally ‘flight of stairs’). The other, ‘escape’, comes from a hypothetical Old English *flyht, never actually recorded, which goes back ultimately to the same Germanic base as produced flee.
=> flee, fly[flight etymology, flight origin, 英语词源]
flight (n.1)youdaoicibaDictYouDict
"act of flying," Old English flyht "a flying, act or power of flying," from Proto-Germanic *flukhtiz (cognates: Dutch vlucht "flight of birds," Old Norse flugr, Old High German flug, German Flug "flight"), from Proto-Germanic *flug-ti-, from PIE *pluk-, from root *pleu- "to flow" (see fly (v.1)).

Spelling altered late 14c. from Middle English fliht (see fight (v.)). Sense of "swift motion" is from mid-13c.. Meaning "an instance of flight" is 1785, originally of ballooning. Sense of "a number of things passing through the air together" is from mid-13c. Meaning "series of stairs between landings" is from 1703. Figuratively, "an excursion" of fancy, imagination, etc., from 1660s. Flight-path is from 1908; flight-test (v.) from 1919; flight-simulator from 1947 (originally in rocketry); flight-attendant from 1946.
flight (n.2)youdaoicibaDictYouDict
"act of fleeing," c. 1200, flihht, not found in Old English, but presumed to have existed and cognate with Old Saxon fluht, Old Frisian flecht "act of fleeing," Dutch vlucht, Old High German fluht, German Flucht, Old Norse flotti, Gothic þlauhs, from Proto-Germanic *flug-ti- (see flight (n.1)). To put (someone or something) to flight "rout, defeat" is from late 14c., the earlier verb form do o' flight (early 13c.).