A bullfrog is a kind of large frog. The one people usually mean is the American bullfrog: a heavy frog that lives in ponds and lakes. The male makes a deep, slow call that people compared to a bull, which is probably how it got the name. It eats almost anything it can fit in its mouth — insects, fish, even smaller frogs. In Taiwan you will meet the word on menus as well as in nature books: people farm 牛蛙 for food, and it has also spread into the wild in some places. It is a frog, not a toad, and it is not a small tree frog.