Word Origin & History
flag1540s, "flap about loosely," perhaps a variant of M.E. flakken, flacken "to flap, flutter," probably from O.N. flakka "to flicker, flutter," perhaps onomatopoeic of something flapping in the wind. Sense of "go limp, droop" is first recorded 1610s. Meaning "to designate as someone who will not be served
EXPANDmore liquor" is from 1980s, probably from use of flags to signal trains, etc., to halt, which led to the verb in this sense (1856). Related: Flagged; flagging.
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