The Oxford Thesaurus An A-Z Dictionary of Synonyms - scowl v.

1) glower, frown, grimace, glare, look daggers, lower or lour: It's hard to tell if he's ever pleased because he's always scowling. --n. 2) frown, grimace, glare, dirty look: I do wish she would wipe that scowl off her face and try to look more pleasant.