(~s)
1.
If you call someone a ~, you mean that they have betrayed beliefs that they used to hold, or that their friends hold, by their words or actions.
Some say he’s a ~ to the working class.
N-COUNT: oft N to n disapproval
2.
If someone is a ~, they betray their country or a group of which they are a member by helping its enemies, especially during time of war.
...rumours that there were ~s among us who were sending messages to the enemy.
N-COUNT