1. (verb)bellow, bellowing, holla, holler, hollering, hollo, holloa, roar, roaring, yowl a very loud utterance (like the sound of an animal) "his bellow filled the hallway"
2. (verb)howl, wrawl, yammer, yowl cry loudly, as of animals "The coyotes were howling in the desert"
3. (verb)yowl, caterwaul utter shrieks, as of cats