The Collaborative International Dictionary of English v.0.48:

Lastage \Last"age\n. [E. lestage ballasting, fr. lest ballast,
   or LL. lastagium, lestagium. See Last a load.]
   1. A duty exacted, in some fairs or markets, for the right to
      carry things where one will. [Obs.]
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   2. A tax on wares sold by the last. [Obs.] --Cowell.
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   3. The lading of a ship; also, ballast. --Spelman.
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   4. Room for stowing goods, as in a ship.
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