es·​trus | \ ˈe-strəs How to pronounce estrus (audio) \

Definition of estrus

: a regularly recurrent state of sexual receptivity during which the female of most mammals will accept the male and is capable of conceiving : heat Some mares will exhibit estrus for 15 to 20 days.— Frederick Harper also : a single occurrence of this state

Examples of estrus in a Sentence

Recent Examples on the Web Unlike female lions, which tend to become receptive to mating—also known as coming into heat, or estrus—at the same time, leopards do not. Doug Main, National Geographic, "Why These Leopard Sisters Are Mating With the Same Male," 27 June 2018 The deer was sixty yards away, moving steadily, its head down, probably following the scent of doe in estrus. New York Times, "‘August,’ by Callan Wink: An Excerpt," 31 Mar. 2020 Based on traces of sperm found in the days before the birth of the first joey, the researchers found that the wallabies’ estrus, or mating period, began before the pregnancy was over. Veronique Greenwood, New York Times, "This Mom Is Still Pregnant. But She’s Already Having Another Baby.," 2 Mar. 2020 During the peak rut, a lot of estrus does mist the woods, and bucks had lots of choices. Michael Hanback, Outdoor Life, "Why Post-Rut is the New Best Time To Hunt Whitetails," 4 Dec. 2019 The animals are in estrus for only 24 to 72 hours each year. Michael E. Ruane, Washington Post, "Could pandas get caught in the U.S.-China trade war?," 27 Aug. 2019 Britain, and Wales in particular, grows lamb at a relatively natural pace, with ewes coming into estrus just once a year, to be mated with rams in the fields, to give birth in the spring, after five months gestation. Washington Post, "Boris Johnson’s no-deal Brexit could lead British lambs to slaughter," 17 Aug. 2019 Females go into estrus for only a couple days annually, and Mei Xiang and her mate, Tian Tian, have previously encountered difficulties with natural conception. Katherine J. Wu, Smithsonian, "Giant Panda Mei Xiang Will Not Give Birth," 5 July 2018 By killing cubs that aren’t his, the male forces the female back into estrus, allowing him to mate and sire cubs of his own. Doug Main, National Geographic, "Why These Leopard Sisters Are Mating With the Same Male," 27 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'estrus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of estrus

circa 1890, in the meaning defined above

History and Etymology for estrus

New Latin, from Latin oestrus gadfly, frenzy, from Greek oistros — more at ire

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Time Traveler for estrus

Time Traveler

The first known use of estrus was circa 1890

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Cite this Entry

“Estrus.” Dictionary, Merriam-Webster, Accessed 24 Sep. 2020.

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More Definitions for estrus


es·​trus | \ ˈes-trəs How to pronounce estrus (audio) \
variants: or estrum \ -​trəm How to pronounce estrum (audio) \ or chiefly British oestrus \ ˈē-​strəs How to pronounce oestrus (audio) \ or oestrum \ ˈē-​strəm How to pronounce oestrum (audio) \

Medical Definition of estrus

1a : a regularly recurrent state of sexual excitability during which the female of most mammals will accept the male and is capable of conceiving : heat
b : a single occurrence of this state

More from Merriam-Webster on estrus

Nglish: Translation of estrus for Spanish Speakers Encyclopedia article about estrus

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