"color," Old English hiw "color; form, appearance; species, kind; beauty," earlier heow, hiow, from Proto-Germanic *hiwam (source also of Old Norse hy "bird's down," Swedish hy "skin, complexion," Gothic hiwi "form, appearance"), from PIE *kiwo-, suffixed form of root *kei- (2), a color adjective of broad application (source also of Sanskrit chawi "hide, skin, complexion, color, beauty, splendor," Lithuanian šyvas "white").
A common word in Old English, squeezed into obscurity after c. 1600 by color (n.) but revived 1850s in chemistry and chromatography, often in a distinctive sense in reference to the quality of color other than luminosity and chroma.