The Collaborative International Dictionary of English v.0.48:

Poundage \Pound"age\, n.
   1. A sum deducted from a pound, or a certain sum paid for
      each pound; a commission.
      [1913 Webster]

   2. A subsidy of twelve pence in the pound, formerly granted
      to the crown on all goods exported or imported, and if by
      aliens, more. [Eng.] --Blackstone.
      [1913 Webster]

   3. (Law) The sum allowed to a sheriff or other officer upon
      the amount realized by an execution; -- estimated in
      England, and formerly in the United States, at so much of
      the pound. --Burrill. Bouvier.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Poundage \Pound"age\, v. t.
   To collect, as poundage; to assess, or rate, by poundage.
   [R.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Poundage \Pound"age\, n. [See 3d Pound.]
   1. Confinement of cattle, or other animals, in a public
      pound.
      [1913 Webster]

   2. A charge paid for the release of impounded cattle.
      [1913 Webster]

WordNet (r) 3.0 (2006):

poundage
    n 1: a charge based on weight measured in pounds
    2: a fee charged for the recovery of impounded animals
    3: weight expressed in pounds
    4: placing private property in the custody of an officer of the
       law [syn: impoundment, impounding, internment,
       poundage]