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1823, medical Latin, from Greek melanosis "a becoming black," from melanoun "to become black," from melas (genitive melanos); see melanin. Related: Melanotic.
melanosis mel·a·no·sis (měl'ə-nō'sĭs)n. Abnormally dark pigmentation of the skin or other tissues, resulting from a disorder of pigment metabolism. Also called melanism.