Source : Webster's Revised Unabridged Dictionary (1913)

Thrall \Thrall\, n. [OE. thral, [thorn]ral, Icel.
   [thorn]r[ae]ll, perhaps through AS. [thorn]r[=ae]l; akin to
   Sw. tr["a]l, Dan. tr[ae]l, and probably to AS.
   [thorn]r[ae]gian to run, Goth. [thorn]ragjan, Gr. tre`chein;
   cf. OHG. dregil, drigil, a servant.]
   1. A slave; a bondman. --Chaucer.

            Gurth, the born thrall of Cedric.     --Sir W.
                                                  Scott.

   2. Slavery; bondage; servitude; thraldom. --Tennyson.

            He still in thrall Of all-subdoing sleep. --Chapman.

   3. A shelf; a stand for barrels, etc. [Prov. Eng.]

Thrall \Thrall\, a.
   Of or pertaining to a thrall; in the condition of a thrall;
   bond; enslaved. [Obs.] --Spenser.

         The fiend that would make you thrall and bond.
                                                  --Chaucer.

Thrall \Thrall\, v. t.
   To enslave. [Obs. or Poetic] --Spenser.

Source : WordNet®

thrall
     n 1: the state of being under the control of another person [syn:
           {bondage}, {slavery}, {thralldom}, {thraldom}]
     2: someone held in bondage