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]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "poundage":
   accommodation, avoirdupois, beef, beefiness, burden, capacity,
   carriage, cartage, content, cordage, deadweight, drayage,
   expressage, fatness, freight, freightage, gravity, gross weight,
   haulage, heaviness, heft, heftiness, limit, liveweight, measure,
   neat weight, net, net weight, overbalance, overweight,
   ponderability, ponderosity, ponderousness, quantity, room, space,
   stowage, tonnage, underweight, volume, weight, weightiness



Bouvier's Law Dictionary, Revised 6th Ed (1856):

POUNDAGE, practice. The amount allowed to the sheriff, or other officer, for
commissions on, the money made by virtue of an execution. This allowance
varies in different states, and to different officers.