The Collaborative International Dictionary of English v.0.48:

Tariff \Tar"iff\, n. [F. tarif; cf. Sp. & Pg. tarifa, It.
   tariffa; all fr. Ar. ta'r[imac]f information, explanation,
   definition, from 'arafa, to know, to inform, explain.]
   1. A schedule, system, or scheme of duties imposed by the
      government of a country upon goods imported or exported;
      as, a revenue tariff; a protective tariff; Clay's
      compromise tariff. (U. S. 1833).
      [1913 Webster]

   Note: The United States and Great Britain impose no duties on
         exports; hence, in these countries the tariff refers
         only to imports.
         [1913 Webster]

   Note: A tariff may be imposed solely for, and with reference
         to, the production of revenue (called a

   revenue tariff, or

   tariff for revenue, or for the artificial fostering of home
      industries (

   a projective tariff), or as a means of coercing foreign
      governments, as in case of

   retaliatory tariff.
      [Webster 1913 Suppl.]

   2. The duty, or rate of duty, so imposed; as, the tariff on
      wool; a tariff of two cents a pound.
      [1913 Webster]

   3. Any schedule or system of rates, changes, etc.; as, a
      tariff of fees, or of railroad fares. --Bolingbroke.
      [1913 Webster]