impost

noun3

1. •
   A tax, tariff or duty that is imposed, especially on merchandise.

   • ’Tis a Land-tax, vvhich he’s too poor to pay; / You, therefore must some other Impost lay. — 1667
2. •
   The top part of a column, pillar, pier, wall, etc. that supports an arch.
3. •
   The weight that must be carried by a horse in a race; the handicap.