1N-PLURAL 卑鄙的人;人渣;败类 If you refer to people as scum, you are expressing your feelings of dislike and disgust for them. 卑鄙的人;人渣;败类 [informal, disapproval]
2N-UNCOUNT (液体表面的)浮渣,浮垢Scum is a layer of a dirty or unpleasant-looking substance on the surface of a liquid. (液体表面的)浮渣,浮垢