oestrus

noun4

1. •
   A female animal's readiness to mate.

   • 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
2. •
   A biting fly of the genus Oestrus; a botfly.

   • […] and which is produced by the larvae of oestri and particularly of Oestrus hemorrhoidalis. — 1915
3. •
   A bite or sting.
4. •
   (no longer used) A passion or frenzy.