The Collaborative International Dictionary of English v.0.48:

Immerse \Im*merse"\, a. [L. immersus, p. p. of immergere. See
   Immerge.]
   Immersed; buried; hid; sunk. [Obs.] "Things immerse in
   matter." --Bacon.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Immerse \Im*merse"\, v. t. [imp. & p. p. Immersed; p. pr. &
   vb. n. Immersing.]
   1. To plunge into anything that surrounds or covers,
      especially into a fluid; to dip; to sink; to bury; to
      immerge.
      [1913 Webster]

            Deep immersed beneath its whirling wave. --J Warton.
      [1913 Webster]

            More than a mile immersed within the wood. --Dryden.
      [1913 Webster]

   2. To baptize by immersion.
      [1913 Webster]

   3. To engage deeply; to engross the attention of; to involve;
      to overhelm.
      [1913 Webster]

            The queen immersed in such a trance.  --Tennyson.
      [1913 Webster]

            It is impossible to have a lively hope in another
            life, and yet be deeply immersed inn the enjoyments
            of this.                              --Atterbury.
      [1913 Webster]

WordNet (r) 3.0 (2006):

immerse
    v 1: thrust or throw into; "Immerse yourself in hot water" [syn:
         immerse, plunge]
    2: devote (oneself) fully to; "He immersed himself into his
       studies" [syn: steep, immerse, engulf, plunge,
       engross, absorb, soak up]
    3: enclose or envelop completely, as if by swallowing; "The huge
       waves swallowed the small boat and it sank shortly
       thereafter" [syn: immerse, swallow, swallow up, bury,
       eat up]
    4: cause to be immersed; "The professor plunged his students
       into the study of the Italian text" [syn: plunge,
       immerse]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "immerse":
   absorb, absorb the attention, arrest, asperge, asperse, baptize,
   bury, busy, catch, charm, christen, deluge, dip, douse, drown,
   duck, dunk, enchant, engage, engage the attention, engage the mind,
   engage the thoughts, engross, engross the mind,
   engross the thoughts, engulf, enthrall, exercise, fascinate, grab,
   grip, hold, hold spellbound, hold the interest, hypnotize, immerge,
   inundate, involve, involve the interest, merge, mesmerize,
   monopolize, obsess, occupy, occupy the attention, overwhelm,
   plunge, plunge in water, preoccupy, saturate, sink, soak, souse,
   spellbind, sprinkle, submerge, submerse, take up, whelm