chromatic (adj.)

1590s (of music), "progressing by half-tones;" 1829 as "pertaining to color," from Latin chromaticus, from Greek khromatikos "relating to color, suited for color," from khroma (genitive khromatos) "color, complexion, character" (but chiefly used metaphorically of embellishments in music), originally "skin, surface" (see chroma). The reason the Greeks used this word in music is not now entirely clear.