From WordNet (r) 3.0 (2006):
rotter
n 1: a person who is deemed to be despicable or contemptible;
"only a rotter would do that"; "kill the rat"; "throw the
bum out"; "you cowardly little pukes!"; "the British call a
contemptible person a `git'" [syn: rotter, dirty dog,
rat, skunk, stinker, stinkpot, bum, puke,
crumb, lowlife, scum bag, so-and-so, git]