Webster's Revised Unabridged Dictionary · 1913

Epizootic

Epizootic , adjective

[Compare French épizootique.]

1.
(Zoology) Of or pertaining to an epizoon.
2.
(Geology) Containing fossil remains; -- said of rocks, formations, mountains, and the like. [Obsolete]
Epizootic mountains are of secondary formation. — Kirwan
3.
Of the nature of a disease which attacks many animals at the same time; -- corresponding to epidemic diseases among men.

Epizootic , noun

[French épizootie.]

1.
A contagious disease which attacks many animals at the same time; an epizootic disease; an epidemic among animals.
2.
A murrain; an epidemic influenza among horses.

Also: Epizooty