pro·​es·​trus (ˌ)prō-ˈe-strəs How to pronounce proestrus (audio)
: a period immediately preceding estrus characterized by preparatory physiological changes

Word History


New Latin

First Known Use

1906, in the meaning defined above

Time Traveler
The first known use of proestrus was in 1906

Dictionary Entries Near proestrus

Cite this Entry

“Proestrus.” Dictionary, Merriam-Webster, Accessed 3 Dec. 2023.

Medical Definition


pro·​es·​trus -ˈes-trəs How to pronounce proestrus (audio)
variants or proestrum or chiefly British pro-oestrus or pro-oestrum
: a preparatory period immediately preceding estrus and characterized by growth of graafian follicles, increased estrogenic activity, and alteration of uterine and vaginal mucosa

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