The Przewalski's horse is now, usually just called a wild horse.

It it the only true wild horse, (very few are left in asia) from which domesticated horse were bred.

American wild horses (Mustangs) are really horses that have escaped and live wild... Feral would be a better word for them, not so the Przewalski's --

i too always had to puzzle of the how to say the name. the Bronx Zoo has a breeding stock, and 50 or so acres for them to run in, not the wilds, but not caged at any rate (the whole of the Zoo is about 350 acrces... pretty big for a city zoo!