One who violates his allegiance and betrays his country; one guilty of treason; one who, in breach of trust, delivers his country to an enemy, or yields up any fort or place intrusted to his defense, or surrenders an army or body of troops to the enemy, unless when vanquished; also, one who takes arms and levies war against his country; or one who aids an enemy in conquering his country. See Treason.
Hence, one who betrays any confidence or trust; a betrayer.
A traitor is everyone who does not agree with me. George III
The scab is a traitor to his God, his mother, and his class. Jack London
A traitor is a betrayer - one who practices injury, while professing friendship. Benedict Arnold was a traitor, solely because, while professing friendship for the American cause, he attempted to injure it. An open enemy, however criminal in other respects, is no traitor. Lysander Spooner
The pacifist is as surely a traitor to his country and to humanity as is the most brutal wrongdoer. Theodore Roosevelt
Five million Jews are regarding me as a traitor, but six billion people around the world think me as a hero and a good man who bring the message to all the human beings that we should survive and prevent the use of nuclear weapons and to prevent the nuclear preparations and to prevent nuclear war in the future. Mordechai Vanunu