The Collaborative International Dictionary of English v.0.48:

Inthrall \In*thrall"\, v. t. [imp. & p. p. Inthralled; p. pr.
   & vb. n. Inthralling.] [Cf. Enthrall.] [Written also
   inthral, enthral, and enthrall.]
   To reduce to bondage or servitude; to make a thrall, slave,
   vassal, or captive of; to enslave.
   [1913 Webster]

         She soothes, but never can inthrall my mind. --Prior.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Enthrall \En*thrall"\, v. t. [Pref. en- + thrall. Cf.
   Inthrall.] [Written also enthral.]
   To hold in thrall; to enslave. See Inthrall.
   [1913 Webster]

         The bars survive the captive they enthrall. --Byron.
   [1913 Webster]

WordNet (r) 3.0 (2006):

enthral
    v 1: hold spellbound [syn: enchant, enrapture, transport,
         enthrall, ravish, enthral, delight] [ant:
         disenchant, disillusion]