impost vs springer

impost and springer both are nouns.

Word	Noun	Adjective	Verb	Adverb
impost	Yes	No	No	No
springer	Yes	No	No	No

As nouns, impost and springer are synonyms defined as:

impost and springer: the lowest stone in an arch -- from which it springs

impost (noun)	springer (noun)
the lowest stone in an arch -- from which it springs	a cow about to give birth
money collected under a tariff	a large spaniel with wavy silky coat usually black or liver and white
	the lowest stone in an arch -- from which it springs