What is sidechick meaning?

The term "sidechick" refers to a woman who is romantically involved with a man who is already in a committed relationship. She is typically aware that the man is in a relationship, but chooses to continue the relationship regardless. The term is often used in a derogatory sense, implying that the woman is engaging in inappropriate and unethical behavior by pursuing a man who is already taken. However, some people argue that the term is unfair and stigmatizes women for engaging in consensual adult relationships.