The Collaborative International Dictionary of English v.0.48:

Entertain \En`ter*tain"\, v. t. [imp. & p. p. Entertained; p.
   pr. & vb. n. Entertaining.] [F. entretenir; entre between
   (L. inter) + tenir to hold, L. tenere. See Tenable.]
   1. To be at the charges of; to take or keep in one's service;
      to maintain; to support; to harbor; to keep.
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            You, sir, I entertain for one of my hundred. --Shak.
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   2. To give hospitable reception and maintenance to; to
      receive at one's board, or into one's house; to receive as
      a guest.
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            Be not forgetful to entertain strangers; for thereby
            some have entertained unawares.       --Heb. xiii.
                                                  2.
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   3. To engage the attention of agreeably; to amuse with that
      which makes the time pass pleasantly; to divert; as, to
      entertain friends with conversation, etc.
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            The weary time she can not entertain. --Shak.
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   4. To give reception to; to receive, in general; to receive
      and take into consideration; to admit, treat, or make use
      of; as, to entertain a proposal.
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            I am not here going to entertain so large a theme as
            the philosophy of Locke.              --De Quincey.
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            A rumor gained ground, -- and, however absurd, was
            entertained by some very sensible people.
                                                  --Hawthorne.
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   5. To meet or encounter, as an enemy. [Obs.] --Shak.
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   6. To keep, hold, or maintain in the mind with favor; to keep
      in the mind; to harbor; to cherish; as, to entertain
      sentiments.
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   7. To lead on; to bring along; to introduce. [Obs.]
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            To baptize all nations, and entertain them into the
            services institutions of the holy Jesus. --Jer.
                                                  Taylor.

   Syn: To amuse; divert; maintain. See Amuse.
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The Collaborative International Dictionary of English v.0.48:

Entertaining \En`ter*tain"ing\, a.
   Affording entertainment; pleasing; amusing; diverting. --
   En`ter*tain"ing*ly, adv. -- En`ter*tain"ing*ness, n.
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WordNet (r) 3.0 (2006):

entertaining
    adj 1: agreeably diverting; "an entertaining puppet show";
           "films should be entertaining"

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "entertaining":
   amusing, beguiling, comic, delightful, diverting, engaging,
   enjoyable, fun, funny, humorous, interesting, pleasant, pleasing,
   pleasurable, recreational, titillating, titillative, witty