Source : Webster's Revised Unabridged Dictionary (1913)

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.

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

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

            I did demand what news from Shrewsbury. --Shak.

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

   4. (Law) To call into court; to summon. --Burrill.

Source : WordNet®

demanding
     adj : 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}]