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[es-truh s] /ˈɛs trəs/
noun, Zoology.
Also, estrum
[es-truh m] /ˈɛs trəm/ (Show IPA),
oestrus. the period of heat or rut; the period of maximum sexual receptivity of the female.
Origin of estrus
1885-90; < Latin oestrus oestrus
Related forms
[es-troo-uh l] /ˈɛs tru əl/ (Show IPA),
adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for estrus


/ˈɛstrəs; ˈiːstrəs/
the usual US spelling of oestrus
Derived Forms
estrous, adjective
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
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Word Origin and History for estrus

1850, "frenzied passion," from Latin oestrus "frenzy, gadfly," from Greek oistros "gadfly, breeze, sting, mad impulse," perhaps from a PIE *eis, forming words denoting passion (cf. Avestan aešma- "anger," Lithuanian aistra "violent passion," Latin ira "anger"). First attested 1890 with specific meaning "rut in animals, heat." Earliest use (1690s) was for "a gadfly." Related: Estrous (1900).

Online Etymology Dictionary, © 2010 Douglas Harper
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estrus in Medicine

estrus es·trus or oes·trus (ěs'trəs)
The periodic state of sexual excitement in the female of most mammals, excluding humans, that immediately precedes ovulation and during which the female is most receptive to mating; heat.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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estrus in Science
A regularly recurring period in female mammals other than humans during which the animal is sexually receptive. Estrus occurs around the time of ovulation. Also called heat.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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