discolor (v.)

late 14c., "alter the proper or natural color of," from Old French descolorer, from des- (see dis-) + colorer "to color," from Latin colorare "to color, to get tanned," from color "color of the skin, color in general" (see color (n.)). Sense of "become discolored" is from 1550s. Related: Discolored; discoloring.