To change or spoil the natural color of something; to stain or cause to lose color.
From dis- (meaning opposite or reversal) + color (from Latin color). The prefix dis- emphasizes the reversal or spoiling of the original color. This word has been used since Middle English.
The prefix dis- is like 'undo'—it reverses or spoils something. So discolor literally means to 'undo' the original color or to damage it, which is why stains and age cause discoloration!
Complete word intelligence in one call. Free tier — 50 lookups/day.