What is another word for turn traitor?
Pronunciation: [tˈɜːn tɹˈe͡ɪtə] (IPA) 
"Turn traitor" is an idiom that means to betray someone or something, particularly a cause or a country one had sworn allegiance to. Synonyms for this phrase include "sell out," "defect," "switch sides," "become a turncoat," "double-cross," "backstab," "betray," and "rat out." All these phrases imply a sense of disloyalty and betrayal towards someone or something that was once trusted and supported. While turn traitor is often used in political or military contexts, these synonyms can be applied to any situation where someone has acted treacherously and betrayed the trust of others.
