oestrus

Etymology

Borrowed from Latin oestrus (“gadfly, sting, frenzy”), from Ancient Greek οἶστρος (oîstros), from Proto-Indo-European *h₁eys-, used to form words denoting passion; see also Latin īra (“anger”), Lithuanian aistra (“violent passion”), Avestan 𐬀𐬈𐬯𐬨𐬀 (aesma, “anger”).

noun

1. A biting fly of the genus Oestrus; a botfly.
   […] and which is produced by the larvae of oestri and particularly of Oestrus hemorrhoidalis. 1915, American Veterinary Review, page 407
   If this is inseparable from the oeconomy of nature, it necessarily follows that man must be subject to the depredations of oestri, ichneumons, . . . and perhaps, thousands of others, which the senses, aided by the directions of a correct understanding, may be able to trace in a way that will fall very little short of absolute demonstration. 1963, Bacteriological Reviews, page 92, column 1
2. A bite or sting.
3. (archaic) A passion or frenzy.
4. (biology) A female animal's readiness to mate; heat, rut.
   In those monoestrous species in which the male is capable all the year round, it is found that the oestri of individual females come at different seasons. 1910, Cleveland Medical Journal, page 517
   A vasectomized Philippine carabao bull was used as a teaser to determine the occurrence and recurrence of oestri. 1939, The Philippine Agriculturist, page 289
   An evaluation was carried out so that the mean number of oestri per one animal was calculated for 14 days in the three periods: […] 1962, Neoplasma, page 152
   Intervals between oestri and between ovulations in dairy cows within 100 days post partum 1980, The Zimbabwe Journal of Agricultural Research, page 73
   It’s the supremely human act, freely to fuck, not because you are on heat, or in oestrus, like an animal, but to give and receive pleasure. 2001, David Lodge, Thinks...
   The substantial genital swelling of [female chimpanzees] during oestrus may facilitate transmission of viruses by making the mucosa more fragile. 2011, Jacques Pepin, “The Source”, in The Origins of AIDS, 1st edition, page 29