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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WordNet (r) 3.0 (2006):

attending
    n 1: the process whereby a person concentrates on some features
         of the environment to the (relative) exclusion of others
         [syn: attention, attending] [ant: inattention]
    2: the act of being present (at a meeting or event etc.) [syn:
       attendance, attending] [ant: nonattendance]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "attending":
   accessory, accompanying, ancillary, associated, attendant,
   coincident, collateral, combined, concomitant, concurrent,
   conjoint, correlative, coupled, fellow, helping, incident, joined,
   joint, menial, ministering, mutual, paired, parallel, satellite,
   servile, serving, servitorial, simultaneous, twin, waiting