before vowels xanth-, word-forming element meaning "yellow," from Greek xanthos "yellow" of various shades; used especially of hair and horses, of unknown origin. Used in scientific words; such as xanthein (1857) "soluble yellow coloring matter in flowers," xanthophyll (1838) "yellow coloring matter in autumn leaves." Also Huxley's Xanthochroi (1867) "blond, light-skinned races of Europe" (with ōkhros "pale").
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Harper, D. (n.d.). Etymology of xanthic. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/xanthic