The Collaborative International Dictionary of English v.0.48:

Rent \Rent\ (r[e^]nt), n. [F. rente, LL. renta, fr. L. reddita,
   fem. sing. or neut. pl. of redditus, p. p. of reddere to give
   back, pay. See Render.]
   1. Income; revenue. See Catel. [Obs.] "Catel had they
      enough and rent." --Chaucer.
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            [Bacchus] a waster was and all his rent
            In wine and bordel he dispent.        --Gower.
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            So bought an annual rent or two,
            And liv'd, just as you see I do.      --Pope.
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   2. Pay; reward; share; toll. [Obs.]
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            Death, that taketh of high and low his rent.
                                                  --Chaucer.
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   3. (Law) A certain periodical profit, whether in money,
      provisions, chattels, or labor, issuing out of lands and
      tenements in payment for the use; commonly, a certain
      pecuniary sum agreed upon between a tenant and his
      landlord, paid at fixed intervals by the lessee to the
      lessor, for the use of land or its appendages; as, rent
      for a farm, a house, a park, etc.
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   Note: The term rent is also popularly applied to compensation
         for the use of certain personal chattels, as a piano, a
         sewing machine, etc.
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   4. (Polit. Econ.)
      (a) That portion of the produce of the earth paid to the
          landlord for the use of the "original and
          indestructible powers of the soil;" the excess of the
          return from a given piece of cultivated land over that
          from land of equal area at the "margin of
          cultivation." Called also economic rent, or
          Ricardian rent. Economic rent is due partly to
          differences of productivity, but chiefly to advantages
          of location; it is equivalent to ordinary or
          commercial rent less interest on improvements, and
          nearly equivalent to ground rent.
      (b) Loosely, a return or profit from a differential
          advantage for production, as in case of income or
          earnings due to rare natural gifts creating a natural
          monopoly.
          [Webster 1913 Suppl.]

   Black rent. See Blackmail, 3.

   Forehand rent, rent which is paid in advance; foregift.

   Rent arrear, rent in arrears; unpaid rent. --Blackstone.

   Rent charge (Law), a rent reserved on a conveyance of land
      in fee simple, or granted out of lands by deed; -- so
      called because, by a covenant or clause in the deed of
      conveyance, the land is charged with a distress for the
      payment of it. --Bouvier.

   Rent roll, a list or account of rents or income; a rental.


   Rent seck (Law), a rent reserved by deed, but without any
      clause of distress; barren rent. A power of distress was
      made incident to rent seck by Statute 4 George II. c. 28.


   Rent service (Eng. Law), rent reserved out of land held by
      fealty or other corporeal service; -- so called from such
      service being incident to it.

   White rent, a quitrent when paid in silver; -- opposed to
      black rent.
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WordNet (r) 3.0 (2006):

economic rent
    n 1: the return derived from cultivated land in excess of that
         derived from the poorest land cultivated under similar
         conditions [syn: economic rent, rent]