oes"trus (?), n. [L., a gadfly; also, frenzy, fr.Gr. gadfly; hence, sting, fury, insane desire, frenzy.]
1. Zool.
A genus of gadflies. The species which deposits its larvae in the nasal cavities of sheep is estrus ovis.
2.
A vehement desire; esp. Physiol., the periodical sexual impulse of animals; heat; rut.
© Webster 1913.