n. The dominant member in a group of girls; a girl who bullies other girls.
2002
Citing new research on teenage relational aggression, a flurry of articles and books have appeared in recent weeks trumpeting the existence of the Alpha Girl (a k a the "really mean girl" or the "queen bee"), a supremely confident, domineering and manipulative teenager, whose main appeal seems to be her stereotypically masculine behavior.
1994 (earliest)
Archer managed to overcome her father's misgivings by promising that he would allow Mary — an archetypal Alpha girl who duly collected an Oxford First — to follow any career she chose.