The Collaborative International Dictionary of English v.0.48:

Demand \De*mand"\, n. [F. demande, fr. demander. See Demand,
   v. t.]
   1. The act of demanding; an asking with authority; a
      peremptory urging of a claim; a claiming or challenging as
      due; requisition; as, the demand of a creditor; a note
      payable on demand.
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            The demand [is] by the word of the holy ones. --Dan.
                                                  iv. 17.
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            He that has confidence to turn his wishes into
            demands will be but a little way from thinking he
            ought to obtain them.                 --Locke.
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   2. Earnest inquiry; question; query. --Shak.
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   3. A diligent seeking or search; manifested want; desire to
      possess; request; as, a demand for certain goods; a
      person's company is in great demand.
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            In 1678 came forth a second edition [Pilgrim's
            Progress] with additions; and then the demand became
            immense.                              --Macaulay.
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   4. That which one demands or has a right to demand; thing
      claimed as due; claim; as, demands on an estate.
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   5. (Law)
      (a) The asking or seeking for what is due or claimed as
          due.
      (b) The right or title in virtue of which anything may be
          claimed; as, to hold a demand against a person.
      (c) A thing or amount claimed to be due.
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   In demand, in request; being much sought after.

   On demand, upon presentation and request of payment.
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WordNet (r) 3.0 (2006):

in demand
    adj 1: greatly desired [syn: coveted, desired, in
           demand(p), sought after]