The Collaborative International Dictionary of English v.0.48:

Absorb \Ab*sorb"\, v. t. [imp. & p. p. Absorbed; p. pr. & vb.
   n. Absorbing.] [L. absorbere; ab + sorbere to suck in, akin
   to Gr. ?: cf. F. absorber.]
   1. To swallow up; to engulf; to overwhelm; to cause to
      disappear as if by swallowing up; to use up; to include.
      "Dark oblivion soon absorbs them all." --Cowper.
      [1913 Webster]

            The large cities absorb the wealth and fashion. --W.
                                                  Irving.
      [1913 Webster]

   2. To suck up; to drink in; to imbibe; as a sponge or as the
      lacteals of the body. --Bacon.
      [1913 Webster]

   3. To engross or engage wholly; to occupy fully; as, absorbed
      in study or the pursuit of wealth.
      [1913 Webster]

   4. To take up by cohesive, chemical, or any molecular action,
      as when charcoal absorbs gases. So heat, light, and
      electricity are absorbed or taken up in the substances
      into which they pass. --Nichol.
      [1913 Webster]

   Syn: To Absorb, Engross, Swallow up, Engulf.

   Usage: These words agree in one general idea, that of
          completely taking up. They are chiefly used in a
          figurative sense and may be distinguished by a
          reference to their etymology. We speak of a person as
          absorbed (lit., drawn in, swallowed up) in study or
          some other employment of the highest interest. We
          speak of a person as ebgrossed (lit., seized upon in
          the gross, or wholly) by something which occupies his
          whole time and thoughts, as the acquisition of wealth,
          or the attainment of honor. We speak of a person
          (under a stronger image) as swallowed up and lost in
          that which completely occupies his thoughts and
          feelings, as in grief at the death of a friend, or in
          the multiplied cares of life. We speak of a person as
          engulfed in that which (like a gulf) takes in all his
          hopes and interests; as, engulfed in misery, ruin,
          etc.
          [1913 Webster]

                That grave question which had begun to absorb
                the Christian mind -- the marriage of the
                clergy.                           --Milman.
          [1913 Webster]

                Too long hath love engrossed Britannia's stage,
                And sunk to softness all our tragic rage.
                                                  --Tickell.
          [1913 Webster]

                Should not the sad occasion swallow up
                My other cares?                   --Addison.
          [1913 Webster]

                And in destruction's river
                Engulf and swallow those.         --Sir P.
                                                  Sidney.
          [1913 Webster]

WordNet (r) 3.0 (2006):

absorb
    v 1: become imbued; "The liquids, light, and gases absorb"
    2: take up mentally; "he absorbed the knowledge or beliefs of
       his tribe" [syn: absorb, assimilate, ingest, take in]
    3: take up, as of debts or payments; "absorb the costs for
       something" [syn: absorb, take over]
    4: take in, also metaphorically; "The sponge absorbs water
       well"; "She drew strength from the minister's words" [syn:
       absorb, suck, imbibe, soak up, sop up, suck up,
       draw, take in, take up]
    5: cause to become one with; "The sales tax is absorbed into the
       state income tax"
    6: suck or take up or in; "A black star absorbs all matter"
       [syn: absorb, take in] [ant: emit, give off, give
       out]
    7: devote (oneself) fully to; "He immersed himself into his
       studies" [syn: steep, immerse, engulf, plunge,
       engross, absorb, soak up]
    8: assimilate or take in; "The immigrants were quickly absorbed
       into society"
    9: consume all of one's attention or time; "Her interest in
       butterflies absorbs her completely" [syn: absorb,
       engross, engage, occupy]

Moby Thesaurus II by Grady Ward, 1.0:

138 Moby Thesaurus words for "absorb":
   ablate, absorb the attention, adsorb, appreciate, apprehend,
   appropriate, arrest, assimilate, be with one, bleed white, blot,
   blot up, burn up, buy up, catch, catch on, catch up in, charm,
   chemisorb, chemosorb, come uppermost, comprehend, conceive,
   concern, consume, corner, deplete, dig, digest, drain,
   drain of resources, draw in, drink, drink in, drink up, eat,
   eat up, embarrass, embody, enchant, engage, engage the attention,
   engage the mind, engage the thoughts, engross, engross the mind,
   engross the thoughts, enmesh, entangle, enthrall, erode, exercise,
   exhaust, expend, fascinate, fathom, fill the mind, filter in,
   finish, finish off, follow, get, get hold of, get the drift,
   get the idea, get the picture, gobble, gobble up, grab, grasp,
   grip, have, have it taped, hold, hold spellbound,
   hold the interest, hypnotize, imbibe, imbue, immerse, implicate,
   impoverish, impregnate, incorporate, infiltrate, infuse, ingest,
   interest, involve, involve the interest, ken, know, learn, master,
   mesmerize, metabolize, monopolize, monopolize the thoughts, obsess,
   obsess the mind, occupy, occupy the attention, occupy the mind,
   osmose, percolate in, permeate, predigest, preoccupy, read,
   realize, savvy, seep in, seize, seize the meaning, seize the mind,
   sense, sew up, slurp up, soak in, soak up, sorb, spellbind, spend,
   sponge, squander, suck dry, suck into, swallow, swallow up,
   swill up, take, take in, take up, tangle, understand, use up,
   waste away, wear away