The Collaborative International Dictionary of English v.0.48:

Self-government \Self`-gov"ern*ment\, n.
   1. The act of governing one's self, or the state of being
      governed by one's self; self-control; self-command.
      [1913 Webster]

   2. Hence, government of a community, state, or nation by the
      joint action of the mass of people constituting such a
      civil body; also, the state of being so governed;
      democratic government; democracy.
      [1913 Webster]

            It is to self-government, the great principle of
            popular representation and administration, -- the
            system that lets in all to participate in the
            councels that are to assign the good or evil to all,
            -- that we may owe what we are and what we hope to
            be.                                   --D. Webster.
      [1913 Webster]

WordNet (r) 3.0 (2006):

self-government
    n 1: government of a political unit by its own people [syn:
         self-government, self-determination, self-rule]