noun: Either of the Grand Trianon and Petit Trianon, two royal palaces constructed in Versailles, France, in the 17th and 18th centuries.
noun: (metonymically, historical) The Treaty of Trianon, a peace treaty signed in the Grand Trianon on 4 June 1920, which formally ended World War I between most of the Allies and the Kingdom of Hungary, leaving Hungary as a landlocked state with less than one-third of its prewar area.