1. involving or guilty of treason; betraying one’s country or government

Examples

• The spy was charged with treasonous activities against the state.
• His treasonous plot to overthrow the government was discovered.
• The court found the defendant guilty of treasonous conduct.
• She refused to participate in any treasonous schemes.
• The general’s treasonous alliance with enemy forces shocked the nation.
• Documents revealed treasonous communications with foreign agents.