Perfidy/ˈpɜːrfədi/ Definition 1 of 2Pro Tip 1/3Trust Breaking Used when someone violates a trust they were supposed to uphold. His perfidy damaged the team's spirit. Pro Tip 2/3Emotional Impact Implies deep emotional hurt caused by the betrayal. Her perfidy left her friend feeling devastated. Pro Tip 3/3Unexpected Twist Often involves a surprise element where betrayal was not anticipated. The perfidy of his closest advisor took the king by surprise.