Im"post (?), n. [OF. impost, F. impot, LL. impostus, fr. L. impostus, p. p. of imponere to impose. See Impone.]
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.
⇒ 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.
© Webster 1913.