IMPOST
springer, impost
(noun) the lowest stone in an arch -- from which it springs
customs, customs duty, custom, impost
(noun) money collected under a tariff
Source: WordNet® 3.1
Etymology 1
Noun
impost (plural imposts)
(chiefly historical) A tax, tariff or duty that is imposed, especially on merchandise.
(horse racing, slang) The weight that must be carried by a horse in a race, the handicap.
Etymology 2
Noun
impost (plural imposts)
The top part of a column, pillar, pier, wall, etc. that supports an arch.
Source: Wiktionary
Im"post, n. Etym: [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.)
Definition: 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.
Source: Webster’s Unabridged Dictionary 1913 Edition