1. a person who betrays someone or something; one who is disloyal or treacherous

Examples

• The spy was revealed to be a betrayer who had sold secrets to the enemy.
• She felt like a betrayer for revealing her friend’s secret.
• History remembers him as a betrayer of his country’s trust.
• The betrayer’s actions caused irreparable damage to the organization.
• He couldn’t forgive the betrayer who had broken their sacred oath.
• The novel’s protagonist discovers that his closest ally is actually a betrayer.