The Collaborative International Dictionary of English v.0.48:

Thrall \Thrall\, a.
   Of or pertaining to a thrall; in the condition of a thrall;
   bond; enslaved. [Obs.] --Spenser.
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         The fiend that would make you thrall and bond.
                                                  --Chaucer.
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The Collaborative International Dictionary of English v.0.48:

Thrall \Thrall\, v. t.
   To enslave. [Obs. or Poetic] --Spenser.
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The Collaborative International Dictionary of English v.0.48:

Thrall \Thrall\, n. [OE. thral, [thorn]ral, Icel.
   [thorn]r[ae]ll, perhaps through AS. [thorn]r[=ae]l; akin to
   Sw. tr[aum]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.
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            Gurth, the born thrall of Cedric.     --Sir W.
                                                  Scott.
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   2. Slavery; bondage; servitude; thraldom. --Tennyson.
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            He still in thrall
            Of all-subdoing sleep.                --Chapman.
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   3. A shelf; a stand for barrels, etc. [Prov. Eng.]
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WordNet (r) 3.0 (2006):

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