He was a 'traitor' who betrayed his country by selling military secrets to the enemy.
He 'turned traitor'. [=he became a traitor; he betrayed his country/friends]
She has been called a 'traitor' to the liberal party's cause.
(..) No, Dustin, we missed it. - I mean that was... - Awesome. It was awesome. Everything I said about you being a traitor and stuff... I was wrong. I'm sorry. Friends... friends don't lie. I'm sorry, too. (..)2016 TvShow: Stranger Things Title: Chapter Seven: The Bathtub Season: 1 Episode 7