Antiestrogen

any of several major female s-x hormones produced primarily by the ovarian follicles of female mammals, capable of inducing , developing and maintaining secondary female s-x characteristics, and preparing the uterus for the reception of a fertilized egg: used, especially in synthetic form, as a component of oral contraceptives, in certain cancer treatments, and in other therapies.
noun
the usual us spelling of oestrogen
n.

coined 1927 from estrus + -gen. so called for the hormone’s ability to produce estrus.

antiestrogen an·ti·es·tro·gen (ān’tē-ěs’trə-jən, ān’tī-)
n.
a substance capable of preventing full expression of the biological effects of an estrogen.

estrogen es·tro·gen or oes·tro·gen (ěs’trə-jən)
n.
any of several natural or synthetic substances formed by the ovary, placenta, testis, and certain plants, that stimulate the female secondary s-x characteristics, exert systemic effects such as the growth and maturation of long bones, and are used to treat disorders due to estrogen deficiency and to ameliorate cancers of the breast and prostate. also called estrin.
estrogen
(ěs’trə-jən)
any of a group of steroid hormones that primarily regulate the growth, development, and function of the female reproductive system. the main sources of estrogen in the body are the ovaries and the placenta. estrogen-like compounds are also formed by certain plants.
estrogen [(es-truh-juhn)]

a group of hormones, secreted mainly by the ovaries, that influence the female reproductive system in many ways, notably in preparing the body for ovulation and in the development of female secondary s-x characteristics.