Estrogen (noun)

1. A female hormone that is produced primarily by the ovaries and responsible for the development and maintenance of female secondary sexual characteristics and the regulation of the menstrual cycle.
2. Any of a group of steroid hormones that are similar in structure to estradiol and that promote the development and maintenance of female secondary sexual characteristics.

Origin:

From the french oestrogène (estrogen), from the greek oistros (madness, frenzy) + -genes (producing), as it was originally thought to cause "estrus" (heat) in animals.

Examples:

1. Estrogen is important for the development of secondary sexual characteristics such as breast development and the regulation of the menstrual cycle.
2. Estrogen levels decrease as women approach menopause.
3. Estrogen replacement therapy is used to treat symptoms of menopause.
4. Estrogen plays an important role in maintaining bone density in women.
5. Estrogen is also produced in small amounts by the adrenal glands and fat cells.