Definition of "high treason" []

• Treason against one's country or sovereign. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Casement's subsequent trial and conviction on a charge of high treason had inspired a movement in his favour from Irish-Americans, the final outcome of which was that the Senate, in early August, passed a resolution asking the British Government for clemency and stipulating that this resolution should be presented to the Foreign Office."
• "When they marched the next year into Champagne to revenge themselves on Tibald, Matthew Paris says that their pretext was that Tibald had been guilty of high treason in being Queen Blanche's paramour, and conspiring with her to poison her husband, Louis VIII."
• "In response, the English Parliament passed a series of vicious laws against Catholics: it became high treason to convert an Anglican to Catholicism, anyone saying or hearing mass was liable to a large fine and a year's imprisonment, - a heavy fine was laid on anyone who failed to attend the Anglican services."