stop over vs stopover

stop over is not a noun while stopover is a noun.

Word	Noun	Adjective	Verb	Adverb
stop over	No	No	Yes	No
stopover	Yes	No	No	No

stop over (noun)	stopover (noun)
	a brief stay in the course of a journey
	a stopping place on a journey

stop over (verb)	stopover (verb)
interrupt a trip
interrupt a journey temporarily, e.g., overnight