Original: Besides the horse, there are seven other species of genus Equus in the Equidae family. These are the ass or donkey, Equus asinus; the mountain zebra, Equus zebra; plains zebra, Equus burchelli; GrÃ vy's zebra, Equus grevyi; the kiang, Equus kiang; and the onager, Equus hemionus.
Simplified: The old Latin word for horse is equus.