"thin flat piece of snow; a particle," early 14c., also flauke, flagge, which is of uncertain origin, possibly from Old English *flacca "flakes of snow," or from cognate Old Norse flak "flat piece," from Proto-Germanic *flakaz (source also of Middle Dutch vlac, Dutch vlak "flat, level," Middle High German vlach, German Flocke "flake"); from PIE root *plak- (1) "to be flat." From late 14c. as "a speck, a spot."
early 15c., flaken, (of snow) "to fall in flakes," from flake (n.). Transitive meaning "break or peel off in flakes" is from 1620s; intransitive sense of "to come off in flakes" is from 1759. . Related: Flaked; flaking.