/ Dictionary / Index T tamoxifen: Meaning and Definition of Find definitions for: ta•mox•i•fen Pronunciation: (tu-mok'su-fun), [key] — n. Pharm. an antineoplastic drug, CHNO, that blocks the estrogen receptors on cancer cells, used in the treatment of breast cancer. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: tamoxifen (Thesaurus) tam-o'-shanter tamp Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language