/ Dictionary / Index M mastectomy: Meaning and Definition of Find definitions for: mas•tec•to•my Pronunciation: (ma-stek'tu-mē), [key] — pl. -mies. the operation of removing all or part of the breast or mamma. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mastectomy (Thesaurus) mast cloth master Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language