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anestrous

American  
[an-es-truhs] / ænˈɛs trəs /
especially British, anoestrous

adjective

Zoology.
  1. not showing a period of heat or rut.

  2. of or relating to the interval of sexual inactivity between two periods of heat or rut.


Etymology

Origin of anestrous

First recorded in 1905–10; an- 1 + estrous