/ Dictionary / Index T teratoma: Meaning and Definition of Find definitions for: ter•a•to•ma Pronunciation: (ter"u-tō'mu), [key] — -mas, -ma•ta a tumor made up of different types of tissue. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: teratoma (Thesaurus) teratology teratosis Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language