estrogen

noun

es·​tro·​gen ˈe-strə-jən 

: any of various natural steroids (such as estradiol) that are formed from androgen precursors, that are secreted chiefly by the ovaries, placenta, adipose tissue, and testes, and that stimulate the development of female secondary sex characteristics and promote the growth and maintenance of the female reproductive system

also : any of various synthetic or semisynthetic steroids (such as ethinyl estradiol) that mimic the physiological effect of natural estrogens

Examples of estrogen in a Sentence

Recent Examples on the Web

During pregnancy, rising estrogen levels keep hair in the growth phase longer, which is why many women experience unusually thick hair. —Allison Palmer, Kansas City Star, 12 Mar. 2026

As estrogen and progesterone levels decrease, the skin loses suppleness and elasticity, resulting in drier, less-bouncy skin that is more susceptible to signs of aging. —Iyana Robertson, Flow Space, 10 Mar. 2026

In addition, higher protein levels in the blood were a stronger predictor of dementia risk in women who took hormone therapy for menopause combining both estrogen and progestin than in women who didn’t use hormones. —Emily Kay Votruba, EverydayHealth.com, 10 Mar. 2026

The study also found that p-tau217 was a stronger predictor of dementia in women who were randomly assigned to receive estrogen and progestin hormone therapy compared to those who received a placebo. —Melissa Rudy, FOXNews.com, 10 Mar. 2026

Word History

Etymology

estrus + -o- + -gen

Note: The word estrogen was originally a U.S. brand name for an extract of glandular tissue used in the treatment of ovarian dysfunction. Its producer, Parke, Davis and Company, relinquished rights to the name in 1936.

First Known Use

1927, in the meaning defined above

Phrases Containing estrogen

• estrogen replacement therapy
• selective estrogen receptor modulator

Kids Definition

estrogen

noun

es·​tro·​gen ˈes-trə-jən 

: a substance that tends to cause the development of secondary sex characteristics in the female and promote the growth and normal functioning of the female reproductive system

estrogenic

ˌes-trə-ˈjen-ik

adjective

Medical Definition

estrogen

noun

es·​tro·​gen ˈes-trə-jən 

variants or chiefly British oestrogen

ˈē-strə-jən 

: any of various natural steroids (as estradiol) that are formed from androgen precursors, that are secreted chiefly by the ovaries, placenta, adipose tissue, and testes, and that stimulate the development of female secondary sex characteristics and promote the growth and maintenance of the female reproductive system

also : any of various synthetic or semisynthetic steroids (as ethinyl estradiol) that mimic the physiological effect of natural estrogens

estrogen-like adjective

or estrogenlike

-ˌlīk 

an estrogen-like compound

estrogen-like effects