- a secret agreement, especially for fraudulent or treacherous purposes; conspiracy: Some of his employees were acting in collusion to rob him.
- a secret understanding between two or more persons to gain something illegally, to defraud someone's rights, or to appear as adversaries though in agreement: collusion of husband and wife to obtain a divorce.
- secret agreement for a fraudulent purpose; connivance; conspiracy
- a secret agreement between opponents at law in order to obtain a judicial decision for some wrongful or improper purpose
