oestrus

The story

1. Proto-Indo-European*h₁eysh₂-
2. Ancient Greekοἶστρος (oîstros)
3. Latinoestrus
4. English todayoestrus

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”).