An unaccompanied female who, while in the presence of a male or males, assumes an angry, scowling face with the intent of discouraging any potential communication with the nearby male/males, as if they had any intent to institute such contact to begin with.
Didn't the expression on that scowlface back there make you think of a car? Myself, I was reminded of a '54 Buick.
1. n. a girl with an overall negative disposition
2. v. the act of scowling at another
1. man that trick is a straight scowlface.
2. i complimented her hair and i straight got scowlfaced.