Anoestrus

Part of speech: noun

Definitions

1. A condition in some female mammals when they show no signs of heat or fertility, resulting in a cessation of estrous cycles and reproductive activity
2. The phase in which certain female animals exhibit a lack of sexual attraction and do not undergo ovulatory processes, leading to interrupted mating opportunities
3. A stage in some female mammals' reproductive cycle marked by absence of sexual receptivity and halted ovulation

Etymology: The word is built from two pieces that come from very different corners of the classical world. Its first part, "an-", is the Greek negative prefix meaning "not" or "without", the same element found in "anarchy" and "anonymous". Its second part, "estrus", is a much older-looking borrowing from Latin "oestrus", which in classical Latin meant a gadfly, the biting insect that drives cattle into frenzied flight. Over the centuries the Latin word also came to mean a frenzy or a sudden urge, and that sense of frantic impulse is what was adopted for the heat of female animals. "Estrus" was therefore named for a restless, goaded state, and "anestrus" simply negates it: the period when that state is absent. The form "anoestrus" is an alternative spelling that keeps the Greek "oe" of the Latin base, which is why both spellings circulate. Anyone who has seen a cow sent wild by a gadfly will recognise the image behind the whole family of terms.