1. That which is imposed or levied; a tax, tribute, or duty; especially, a duty or tax laid by goverment on goods imported into a country.
Even the ship money . . . Johnson could not pronounce to have been an unconstitutional impost. --Macaulay.
2. Arch. The top member of a pillar, pier, wall, etc., upon which the weight of an arch rests.
Note: ☞ The impost is called continuous, if the moldings of the arch or architrave run down the jamb or pier without a break.
Syn: -- Tribute; excise; custom; duty; tax.
n 1: money collected under a tariff [syn: customs, customs
2: the lowest stone in an arch -- from which it springs [syn: springer]