Supremacy, n.
Etymology: [Cf. F. suprématie. See Supreme.]
The state of being supreme, or in the highest station of power; highest or supreme authority or power; as, the supremacy of a king or a parliament. The usurped power of the pope being destroyed, the crown was restored to its supremacy over spiritual men and causes. Blackstone. Oath supremacy, an oath which acknowledges the supremacy of the sovereign in spiritual affairs, and renounced or abjures the supremacy of the pope in ecclesiastical or temporal affairs. [Eng.] Brande & C.
Shades of meaning
Fernald has no entry of its own for supremacy; he lists it under victory.
He lists it without comment; the entries above explain its neighbors.