Is it possible for a citizen to commit treason; and if so what actions would be determined to be treason?

in law, treason is the crime that covers some of the more serious acts of disloyalty to one's sovereign or nation. Historically, treason also covered the murder of specific social superiors, such as the murder of a husband by his wife (treason against the king was known as high treason and treason against a lesser superior was petit treason). A person who commits treason is known as a traitor.