Discoloration

wiktionary

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From discolor or discolour +‎ -ation

etymonline

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discoloration (n.)

1640s, "action of altering the natural or proper color of; condition of being discolored," noun of action from discolorate (early 15c.), from past-participle stem of Medieval Latin discolorare, from Latin dis- "off, away from" (see dis-) + colorare "to color," from color "color of the skin, color in general" (see color (n.)).