cloud up vs cloud

cloud up is not a noun while cloud is a noun.

Word	Noun	Adjective	Verb	Adverb
cloud up	No	No	Yes	No
cloud	Yes	No	Yes	No

cloud up (noun)	cloud (noun)
	a group of many things in the air or on the ground
	a visible mass of water or ice particles suspended at a considerable altitude
	any collection of particles (e.g., smoke or dust) or gases that is visible
	suspicion affecting your reputation
	out of touch with reality
	a cause of worry or gloom or trouble

cloud up (verb)	cloud (verb)
become covered with clouds	colour with streaks or blotches of different shades
	make milky or dull
	make less clear
	place under suspicion or cast doubt upon
	make gloomy or depressed
	billow up in the form of a cloud
	make less visible or unclear
	make overcast or cloudy