/ Dictionary / Index M melanosis: Meaning and Definition of Find definitions for: mel•a•no•sis Pronunciation: (mel"u-nō'sis), [key] — n. Pathol. abnormal deposition or development of black or dark pigment in the tissues. a discoloration caused by this. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: melanosis (Thesaurus) melanophore melanosome Related Content Daily Word Quiz: feline Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language