"Mean girls" refers to unkind girls, often through indirect bullying, such as excluding others by intentionally leaving someone out of social events, conversations, or group activities, spreading rumors or false or negative information about someone, and manipulation, which involves using others to their advantage, including turning people against each other, giving backhanded comliments that are compliments that are actually disguised insults and by Deliberately embarrassing or degrading someone.
The term can also refer to the character archetype in pop culture or a group that exerts a negative social hierarchy. This behavior, also known as relational aggression, can be a coping mechanism stemming from insecurity or a learned response from observing others.