The Collaborative International Dictionary of English v.0.48:

Engross \En*gross"\, v. t. [imp. & p. p. Engrossed; p. pr. &
   vb. n. Engrossing.] [F., fr. pref. en- (L. in) + gros
   gross, grosse, n., an engrossed document: cf. OF. engrossir,
   engroissier, to make thick, large, or gross. See Gross.]
   1. To make gross, thick, or large; to thicken; to increase in
      bulk or quantity. [Obs.]
      [1913 Webster]

            Waves . . . engrossed with mud.       --Spenser.
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            Not sleeping, to engross his idle body. --Shak.
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   2. To amass. [Obs.]
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            To engross up glorious deeds on my behalf. --Shak.
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   3. To copy or write in a large hand (en gross, i. e., in
      large); to write a fair copy of in distinct and legible
      characters; as, to engross a deed or like instrument on
      parchment.
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            Some period long past, when clerks engrossed their
            stiff and formal chirography on more substantial
            materials.                            --Hawthorne.
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            Laws that may be engrossed on a finger nail. --De
                                                  Quincey.
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   4. To seize in the gross; to take the whole of; to occupy the
      attention completely; to absorb; as, the subject engrossed
      all his thoughts.
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   5. To purchase either the whole or large quantities of, for
      the purpose of enhancing the price and making a profit;
      hence, to take or assume in undue quantity, proportion, or
      degree; as, to engross commodities in market; to engross
      power.
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   Engrossed bill (Legislation), one which has been plainly
      engrossed on parchment, with all its amendments,
      preparatory to final action on its passage.

   Engrossing hand (Penmanship), a fair, round style of
      writing suitable for engrossing legal documents,
      legislative bills, etc.

   Syn: To absorb; swallow up; imbibe; consume; exhaust; occupy;
        forestall; monopolize. See Absorb.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

engrossing \engrossing\ adj.
   capable of holding the attention completely; very
   interesting.

   Syn: absorbing, fascinating, gripping, riveting.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

engrossing
    adj 1: capable of arousing and holding the attention; "a
           fascinating story" [syn: absorbing, engrossing,
           fascinating, gripping, riveting]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "engrossing":
   absorbing, all-consuming, arresting, attractive, consuming,
   controlling, enchanting, engaging, enthralling, exciting,
   fascinating, gripping, holding, hypnotic, interesting, intriguing,
   magnetic, mesmeric, mesmerizing, monopolizing, obsessing,
   obsessive, preoccupying, provoking, spellbinding, stimulating