Main Entry: es·trus

Pronunciation: \ˈes-trəs\

Function: noun

Etymology: New Latin, from Latin oestrus gadfly, frenzy, from Greek oistros — more at ire

Date: circa 1890

: a regularly recurrent state of sexual excitability during which the female of most mammals will accept the male and is capable of conceiving : heat; also : a single occurrence of this state