1. Hist. The power of a feudal overlord to whom fealty is due. See FEALTY.
2. Int’l law. The dominion of a nation that controls the foreign relations of another nation but allows it autonomy in its domestic affairs.
“At the present time there appears to be no instance of a relation between states which is described as a suzerainty. The term was applied to the relation between Great Britain and the South African Republic, and also to that between Turkey and Bulgaria from 1878 to 1909, but it seems likely to disappear from diplomatic terminology.” J.L. Brierly, The Law of Nations 128 (5th ed. 1955).