tamoxifen tam-o-shantered • Tamoyo · · · Info · Definitions · Synonyms · Characters · · tamoxifen · · Text Latin · · Script 9 · · Length 4 · · Syllables Definitions · · · (noun) an antagonist for estrogen that is used in the treatment of breast cancer. Synonyms: estrogen antagonist. · · Noun Definition 1 Synonyms · · · estrogen antagonist · · Synonym 1 Characters · · a latin small letter a U+0061 e latin small letter e U+0065 f latin small letter f U+0066 i latin small letter i U+0069 m latin small letter m U+006D n latin small letter n U+006E o latin small letter o U+006F t latin small letter t U+0074 x latin small letter x U+0078