postposition vs postpose

postposition is a noun but postpose is not a noun.

Word	Noun	Adjective	Verb	Adverb
postposition	Yes	No	No	No
postpose	No	No	Yes	No

postposition (noun)	postpose (noun)
(linguistics) the placing of one linguistic element after another (as placing a modifier after the word that it modifies in a sentence or placing an affix after the base to which it is attached)

postposition (verb)	postpose (verb)
	place after another constituent in the sentence