Origin: Anc Greek
οίστρος/estros(=estrus, gadfly, frenzy, inspiration) > οίσω/esso(=future tense of verb φέρω/phero=carry)
1. Oestrus is the genus name of the gadfly insect that annoys horses.
2. Estrus is the time during the reproductive cycle in animals, excluding humans, in which the female displays intense sexual urge(sexual excitement or heat).