flag 词源(Etymology) - 趣词词源[英文版]

flag [flag 词源字典]: flag: English has at least three separate words flag, none of whose origins are known for certain. Both the noun ‘cloth used as an emblem’ [16] and the verb ‘droop, decline’ [16] may have developed from an obsolete 16th-century adjective flag ‘drooping, hanging down’, but no one knows where that came from. Flag the plant [14] is probably related to Danish flæg ‘yellow iris’, but beyond that the trail goes cold. Flag as in flag-stone [15] originally meant ‘piece of turf’.

It probably came from Old Norse flaga ‘stone slab’. This also gave English flaw (which originally meant ‘flake’), which is related to English floe, and goes back to a Germanic base, a variant of which produced English flake.
=> flake, flaw, floe[flag etymology, flag origin, 英语词源]
flag (n.1): "cloth ensign," late 15c., now in all modern Germanic languages (German Flagge, Dutch vlag, Danish flag, Swedish flagg, etc.) but apparently first recorded in English, of unknown origin, but likely connected to flag (v.1) or else an independent imitative formation "expressing the notion of something flapping in the wind" [OED]. A guess considered less likely is that it is from flag (n.2) on the notion of being square and flat.

Meaning "name and editorial information on a newspaper" is by 1956. U.S. Flag Day (1894) is in reference to the adopting of the Stars and Stripes by the Continental Congress on June 14, 1777.
flag (v.1): 1540s, "flap about loosely," probably a later variant of Middle English flakken, flacken "to flap, flutter" (late 14c.), which probably is from Old Norse flaka "to flicker, flutter, hang losse," perhaps imitative of something flapping lazily in the wind. Sense of "go limp, droop, become languid" is first recorded 1610s. Related: Flagged; flagging.
flag (n.2): "flat stone for paving," c. 1600, ultimately from Old Norse flaga "stone slab," from Proto-Germanic *flago- (see flake (n.)). Earlier in English as "piece cut from turf or sod" (mid-15c.), from Old Norse flag "spot where a piece of turf has been cut out," from flaga.
flag (n.3): plant growing in moist places, late 14c., "reed, rush," perhaps from Scandinavian (compare Danish flæg "yellow iris") or from Dutch flag; perhaps ultimately connected to flag (v.1) on notion of "fluttering in the breeze."
flag (v.2): 1875, "place a flag on or over," from flag (n.1). Meaning "designate as someone who will not be served more liquor," by 1980s, probably from use of flags to signal trains, etc., to halt, which led to a verb meaning "inform by means of signal flags" (1856, American English). Meaning "to mark so as to be easily found" is from 1934 (originally by means of paper tabs on files). Related: Flagged; flagging.