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):

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

Moby Thesaurus II by Grady Ward, 1.0:

85 Moby Thesaurus words for "enthrall":
   absorb, absorb the attention, arrest, becharm, beguile, bewitch,
   captivate, carry away, cast a spell, catch, catch up, charm,
   delectate, delight, deprive of freedom, disenfranchise,
   disfranchise, dominate, enchant, engage, engage the attention,
   engage the mind, engage the thoughts, engross, engross the mind,
   engross the thoughts, enrapture, enravish, enslave, entrance,
   exercise, fascinate, freak out, grab, grip, hold, hold captive,
   hold down, hold in bondage, hold in captivity, hold in leash,
   hold in subjection, hold spellbound, hold the interest, hypnotize,
   immerse, imparadise, infatuate, intrigue, involve,
   involve the interest, keep down, keep under, knock dead, knock out,
   lead captive, make dependent, master, mesmerize, monopolize,
   obsess, occupy, occupy the attention, peonize, preoccupy, ravish,
   send, slay, spell, spellbind, subdue, subject, subjugate,
   subordinate, take captive, take up, thrill, tickle, tickle pink,
   titillate, transport, vamp, vassalize, witch, wow