late 14c., "to spot, stain, cover with spots," probably from Old Norse flekka "to spot," from Proto-Germanic *flekk- (cognates: Middle Dutch vlecke, Old High German flec, German Fleck), from PIE *pleik- "to tear" (see flay). Related: Flecked; flecking.

1590s, "a mark on skin, a freckle," of uncertain origin; perhaps from fleck, v. or else from a related word elsewhere in Germanic, such as Middle Dutch vlecke or Old Norse flekkr "a fleck, spot." From 1750 as "small particle," 1804 as "a patch, a spot" of any kind.