progesterone

noun

pro·​ges·​ter·​one prō-ˈje-stə-ˌrōn 

: a female steroid sex hormone C₂₁H₃₀O₂ that is secreted by the corpus luteum to prepare the endometrium for implantation and later by the placenta during pregnancy to prevent rejection of the developing embryo or fetus

Examples of progesterone in a Sentence

Recent Examples on the Web

The decision noted that natural progesterone is used off-label for many conditions in women’s health, but the state outlawed only the choice of women to use it for APR. —Dp Opinion, Denver Post, 16 Feb. 2026

After your baby is born progesterone (which inhibits breastmilk production) drops and prolactin, which controls milk volume, and oxytocin, which triggers the let-down reflex increases, explains Nadine Rosenblum, the perinatal lactation program coordinator at The Johns Hopkins Hospital. —Hannah Silverman, Parents, 16 Feb. 2026

Drops in estrogen and progesterone also affect immune activity, resulting in more inflammation that could promote more sneezing, itching, and hives—or even being diagnosed with allergies for the first time during perimenopause. —Jocelyn Solis-Moreira, Flow Space, 13 Feb. 2026

Women who begin menstruating early — especially before age 12 — and therefore have more menstrual cycles over their lifetime have a slightly higher risk for breast cancer, likely because they’re exposed to the hormones estrogen and progesterone for longer, according to the American Cancer Society. —Miriam Fauzia, Dallas Morning News, 10 Feb. 2026

Word History

Etymology

blend of progestin and luteosterone (borrowed from German Luteosteron, from luteo- luteo- + -steron -sterone), both earlier names for progesterone

Note: The name resulted from a compromise between researchers associated with the earlier names, the American gynecologist Willard M. Allen and embryologist George Washington Corner, and the German biochemists Adolph Butenandt and Karl Heinrich Slotta. See W. M. Allen, A. Butenandt, G. W. Corner, and K. H. Slotta, "Nomenclature of Corpus Luteum Hormone," Nature, vol. 136, number 303 (September 1, 1935), p. 303.

First Known Use

1935, in the meaning defined above

Rhymes for progesterone

• aldosterone
• anticyclone
• testosterone
• acetone
• anglophone
• baritone
• bourguignon
• buspirone
• chaperon
• chaperone
• cobblestone
• collarbone

Kids Definition

progesterone

noun

pro·​ges·​ter·​one prō-ˈjes-tə-ˌrōn 

: a hormone that is produced by the corpus luteum and causes the uterus to change so that it provides a suitable environment for a fertilized egg

Medical Definition

progesterone

noun

pro·​ges·​ter·​one prō-ˈjes-tə-ˌrōn 

: a female steroid sex hormone C₂₁H₃₀O₂ that is secreted by the corpus luteum to prepare the endometrium for implantation and later by the placenta during pregnancy to prevent rejection of the developing embryo or fetus

Note: Synthetic steroids (such as progestins) that function similarly in the body are sometimes also referred to as progesterones.