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.

2. (Arch.) The top member of a pillar, pier, wall, etc., upon which the weight of an arch rests.

&fist; 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.

• a tax, tariff or duty etc. that is imposed
  
• the weight that must be carried by a horse in a race, the handicap.
  
• the top part of a column or pillar that supports an arch