The Collaborative International Dictionary of English v.0.48:

Demand \De*mand"\, v. t. [imp. & p. p. Demanded; p. pr. & vb.
   n. Demanding.] [F. demander, LL. demandare to demand,
   summon, send word, fr. L. demandare to give in charge,
   intrust; de- + mandare to commit to one's charge, commission,
   order, command. Cf. Mandate, Commend.]
   1. To ask or call for with authority; to claim or seek from,
      as by authority or right; to claim, as something due; to
      call for urgently or peremptorily; as, to demand a debt;
      to demand obedience.
      [1913 Webster]

            This, in our foresaid holy father's name,
            Pope Innocent, I do demand of thee.   --Shak.
      [1913 Webster]

   2. To inquire authoritatively or earnestly; to ask, esp. in a
      peremptory manner; to question.
      [1913 Webster]

            I did demand what news from Shrewsbury. --Shak.
      [1913 Webster]

   3. To require as necessary or useful; to be in urgent need
      of; hence, to call for; as, the case demands care.
      [1913 Webster]

   4. (Law) To call into court; to summon. --Burrill.
      [1913 Webster]

WordNet (r) 3.0 (2006):

demanding
    adj 1: requiring more than usually expected or thought due;
           especially great patience and effort and skill; "found
           the job very demanding"; "a baby can be so demanding"
           [ant: undemanding]