The Collaborative International Dictionary of English v.0.48:

Subjugate \Sub"ju*gate\, v. t. [imp. & p. p. Subjugated; p.
   pr. & vb. n. Subjugating.] [L. subjugatus, p. p. of
   subjugare to subjugate; sub under + jugum a yoke. See
   Yoke.]
   To subdue, and bring under the yoke of power or dominion; to
   conquer by force, and compel to submit to the government or
   absolute control of another; to vanquish.
   [1913 Webster]

         He subjugated a king, and called him his "vassal."
                                                  --Baker.
   [1913 Webster]

   Syn: To conquer; subdue; overcome. See Conquer.
        [1913 Webster]

WordNet (r) 3.0 (2006):

subjugated
    adj 1: reduced to submission; "subjugated peoples"

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "subjugated":
   bond, broken, captive, conquered, crushed, disenfranchised,
   enslaved, enthralled, felled, flattened, humbled, in bondage,
   in bonds, in captivity, in chains, in slavery, in subjection,
   mastered, oppressed, put down, quelled, reduced, smashed, subdued,
   subjected, suppressed, under the heel, under the lash, unfree,
   vanquished