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.
(..) but she may be using a different name. Starks? What, like them lot from "Winterhell"? No, ain't seen anyone like that. I heard they was all traitors. Don't need no traitors in here. I swore to her I'd bring her daughters home. Sure I can't get you a bit more kidney pie? What? It's nothing, my lady. (..)2014 TvShow: Game of Thrones Title: Mockingbird Season: 4 Episode 7