The Collaborative International Dictionary of English v.0.48:

Taxation \Tax*a"tion\, n. [F. taxation, L. taxatio a valuing,
   estimation, from L. taxare. See Tax.]
   1. The act of laying a tax, or of imposing taxes, as on the
      subjects of a state, by government, or on the members of a
      corporation or company, by the proper authority; the
      raising of revenue; also, a system of raising revenue.
      [1913 Webster]

   2. (Law) The act of taxing, or assessing a bill of cost.
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   3. Tax; sum imposed. [R.] --Daniel.
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   4. Charge; accusation. [Obs.] --Shak.
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WordNet (r) 3.0 (2006):

taxation
    n 1: charge against a citizen's person or property or activity
         for the support of government [syn: tax, taxation,
         revenue enhancement]
    2: government income due to taxation [syn: tax income,
       taxation, tax revenue, revenue]
    3: the imposition of taxes; the practice of the government in
       levying taxes on the subjects of a state