the doctrine that sovereign power is vested in the people and that those chosen to govern, as trustees of such power, must exercise it in conformity with the general will.
American History. (before the Civil War) a doctrine, held chiefly by the opponents of the abolitionists, that the people living in a territory should be free of federal interference in determining domestic policy, especially with respect to slavery.
British Dictionary definitions for popular-sovereignty
(in the pre-Civil War US) the doctrine that the inhabitants of a territory should be free from federal interference in determining their own domestic policy, esp in deciding whether or not to allow slavery