WordNet sense 1 (the matter ejected in vomiting):

barf, vomit, vomitus

WordNet sense 2 (a person who is deemed to be despicable or contemptible):

bum, crumb, lowlife, rat, skunk, so-and-so, stinker, git, rotter, stinkpot, dirty dog

WordNet sense 3 (eject the contents of the stomach through the mouth):

cast, cat, chuck, disgorge, honk, purge, regurgitate, retch, sick, spew, upchuck, regorge, spue, be sick, throw up, vomit up