Tamoxifen is a drug that is used to treat breast cancer, most commonly in women. It is a type of hormonal therapy drug. There are several synonyms for tamoxifen, including Nolvadex, istubal, Tamosin, Tamone, and Valodex. Each of these drugs has the same active ingredient as tamoxifen and is used to treat breast cancer. Nolvadex is the most well-known synonym for tamoxifen and is often prescribed to women who have been diagnosed with breast cancer. It is important to note that tamoxifen and its various synonyms should only be taken with a doctor's prescription and under supervision due to potential side effects.