Flaw
Middle English: perhaps from Old Norse flaga ‘slab’. The original sense was ‘a flake of snow’, later, ‘a fragment or splinter’, hence ‘a defect or imperfection’ (late 15th century).
wiktionary
From Middle English flawe, flay(“a flake of fire or snow, spark, splinter”), probably from Old Norse flaga(“a flag or slab of stone, flake”), from Proto-Germanic *flagō(“a layer of soil”), from Proto-Indo-European *plāk-(“broad, flat”). Cognate with Icelandic flaga(“flake”), Swedish flaga(“flake, scale”), Danish flage(“flake”), Middle Low German vlage(“a layer of soil”), Old English flōh(“a frament, piece”).
Probably Middle Dutch vlāghe or Middle Low German vlāge. [1] Or, of North Germanic origin, from Swedish flaga(“gust of wind”), from Old Norse flaga; [2] all from Proto-Germanic *flagōn-. See modern Dutch vlaag(“gust of wind”).
etymonline
flaw (n.)
early 14c., "a flake" (of snow), also in Middle English "a spark of fire; a splinter," from Old Norse flaga "stone slab, layer of stone" (see flag (n.2)), perhaps used here in an extended sense. Old English had floh stanes, but the Middle English form suggests a Scandinavian origin. "The close resemblance in sense between flaw and flake is noteworthy" [OED]. Sense of "defect, fault" first recorded 1580s, first of character, later (c. 1600) of material things; probably via notion of a "fragment" broken off.
flaw (v.)
"cause a flaw or defect in," early 15c. (implied in flawed); see flaw (n.). Related: Flawing.
