postpose vs postposition

postpose is not a noun while postposition is a noun.

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

postpose (noun)	postposition (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)

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