The Collaborative International Dictionary of English v.0.48:

Junta \Jun"ta\ (j[u^]n"t[.a]), n.; pl. Juntas (j[u^]n"t[.a]z).
   [Sp., fr. L. junctus joined, p. p. of jungere to join. See
   Join, and cf. Junto.]
   1. A council; a convention; a tribunal; an assembly; esp.,
      the grand council of state in Spain.
      [1913 Webster]

   2. A junto.
      [PJC]

   3. A small committee or group self-appointed to serve as the
      government of a country, usually just after a coup d'etat
      or revolution, and often composed primarily of military
      men. The term is used mostly in Latin American countries.
      [PJC]

WordNet (r) 3.0 (2006):

junta
    n 1: a group of military officers who rule a country after
         seizing power [syn: military junta, junta]