oestrogen

British

/ ˌɛstrəˈdʒɛnɪk, ˌiːstrəˈdʒɛnɪk, ˈɛstrə-, ˌiːstrə-, ˌɛstrə-, ˈiːstrədʒən /

noun

any of several steroid hormones, that are secreted chiefly by the ovaries and placenta, that induce oestrus, stimulate changes in the female reproductive organs during the oestrous cycle, and promote development of female secondary sexual characteristics

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Etymology

Origin of oestrogen

C20: from _oestrus + _-gen

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

That reaction is mainly driven by changes in progesterone levels, which peak, and oestrogen, which fluctuates, triggering strong feelings of despair, loss and a lack of control.

From BBC • May 16, 2026

Letrozole is a drug used to lower oestrogen levels and is frequently used to treat breast cancer.

From BBC • Apr. 3, 2026

Scans and biopsies followed, and a week and a half later she was given a diagnosis of oestrogen receptor-positive breast cancer.

From BBC • Feb. 9, 2026

The pill is an oral selective oestrogen receptor, designed to fight tumors driven by the hormone estrogen, which are estimated to account for up to 70% of all breast cancer cases.

From The Wall Street Journal • Nov. 18, 2025

We can give you some other pills that will give your body the oestrogen it ought to be producing.

From Identity by Frikki, Aiko

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023