/ Dictionary / Index T teratogen: Meaning and Definition of Find definitions for: te•rat•o•gen Pronunciation: (tu-rat'u-jun, -jen", ter'u-tu-), [key] — n. Biol. a drug or other substance capable of interfering with the development of a fetus, causing birth defects. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: teratogen (Thesaurus) terato- teratogenesis Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language