The Collaborative International Dictionary of English v.0.48:

Sovereignty \Sov"er*eign*ty\, n.; pl. Sovereignties. [OE.
   soverainetee, OF. sovrainet['e], F. souverainet['e].]
   The quality or state of being sovereign, or of being a
   sovereign; the exercise of, or right to exercise, supreme
   power; dominion; sway; supremacy; independence; also, that
   which is sovereign; a sovereign state; as, Italy was formerly
   divided into many sovereignties.
   [1913 Webster]

         Woman desiren to have sovereignty
         As well over their husband as over their love.
                                                  --Chaucer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sovereignty
    n 1: government free from external control
    2: royal authority; the dominion of a monarch [syn: reign,
       sovereignty]
    3: the authority of a state to govern another state