The Collaborative International Dictionary of English v.0.48:

Attend \At*tend"\, v. t. [imp. & p. p. Attended; p. pr. & vb.
   n. Attending.] [OE. atenden, OF. atendre, F. attendre, to
   expect, to wait, fr. L. attendre to stretch, (sc. animum), to
   apply the mind to; ad + tendere to stretch. See Tend.]
   1. To direct the attention to; to fix the mind upon; to give
      heed to; to regard. [Obs.]
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            The diligent pilot in a dangerous tempest doth not
            attend the unskillful words of the passenger. --Sir
                                                  P. Sidney.
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   2. To care for; to look after; to take charge of; to watch
      over.
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   3. To go or stay with, as a companion, nurse, or servant; to
      visit professionally, as a physician; to accompany or
      follow in order to do service; to escort; to wait on; to
      serve.
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            The fifth had charge sick persons to attend.
                                                  --Spenser.
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            Attends the emperor in his royal court. --Shak.
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            With a sore heart and a gloomy brow, he prepared to
            attend William thither.               --Macaulay.
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   4. To be present with; to accompany; to be united or
      consequent to; as, a measure attended with ill effects.
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            What cares must then attend the toiling swain.
                                                  --Dryden.
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   5. To be present at; as, to attend church, school, a concert,
      a business meeting.
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   6. To wait for; to await; to remain, abide, or be in store
      for. [Obs.]
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            The state that attends all men after this. --Locke.
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            Three days I promised to attend my doom. --Dryden.
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   Syn: To Attend, Mind, Regard, Heed, Notice.

   Usage: Attend is generic, the rest are specific terms. To
          mind is to attend so that it may not be forgotten; to
          regard is to look on a thing as of importance; to heed
          is to attend to a thing from a principle of caution;
          to notice is to think on that which strikes the
          senses. --Crabb. See Accompany.
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The Collaborative International Dictionary of English v.0.48:

Attend \At*tend"\, v. i.
   1. To apply the mind, or pay attention, with a view to
      perceive, understand, or comply; to pay regard; to heed;
      to listen; -- usually followed by to.
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            Attend to the voice of my supplications. --Ps.
                                                  lxxxvi. 6.
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            Man can not at the same time attend to two objects.
                                                  --Jer. Taylor.
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   2. To accompany or be present or near at hand, in pursuance
      of duty; to be ready for service; to wait or be in
      waiting; -- often followed by on or upon.
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            He was required to attend upon the committee.
                                                  --Clarendon.
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   3. (with to) To take charge of; to look after; as, to attend
      to a matter of business.
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   4. To wait; to stay; to delay. [Obs.]
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            For this perfection she must yet attend,
            Till to her Maker she espoused be.    --Sir J.
                                                  Davies.
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   Syn: To Attend, Listen, Hearken.

   Usage: We attend with a view to hear and learn; we listen
          with fixed attention, in order to hear correctly, or
          to consider what has been said; we hearken when we
          listen with a willing mind, and in reference to
          obeying.
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WordNet (r) 3.0 (2006):

attend
    v 1: be present at (meetings, church services, university),
         etc.; "She attends class regularly"; "I rarely attend
         services at my church"; "did you go to the meeting?" [syn:
         attend, go to] [ant: miss]
    2: take charge of or deal with; "Could you see about lunch?"; "I
       must attend to this matter"; "She took care of this business"
       [syn: attend, take care, look, see]
    3: to accompany as a circumstance or follow as a result;
       "Menuhin's playing was attended by a 15-minute standing
       ovation"
    4: work for or be a servant to; "May I serve you?"; "She attends
       the old lady in the wheelchair"; "Can you wait on our table,
       please?"; "Is a salesperson assisting you?"; "The minister
       served the King for many years" [syn: serve, attend to,
       wait on, attend, assist]
    5: give heed (to); "The children in the audience attended the
       recital quietly"; "She hung on his every word"; "They
       attended to everything he said" [syn: attend, hang,
       advert, pay heed, give ear]