A violation of allegiance can be referred to as disloyalty, treason, treachery, or betrayal. Disloyalty implies a breach of faith, especially in rejecting loyalty to a person or nation. Treason is typically defined as an act of betrayal against one's country or government, often punishable by death. Treachery refers to a violation of trust, especially in a political or military context. Betrayal also suggests a breach of trust or faith, either in a person or in an ideal. All the above synonyms convey the idea of breaking a solemn promise or oath of loyalty, be it to a person, a group, or a country.