unscrew vs screw

unscrew is not a noun while screw is a noun.

Word	Noun	Adjective	Verb	Adverb
unscrew	No	No	Yes	No
screw	Yes	No	Yes	No

unscrew (noun)	screw (noun)
	slang for sexual intercourse
	a fastener with a tapered threaded shank and a slotted head
	a propeller with several angled blades that rotates to push against water or air
	a simple machine of the inclined-plane type consisting of a spirally threaded cylindrical rod that engages with a similarly threaded hole
	someone who guards prisoners

unscrew (verb)	screw (verb)
loosen something by unscrewing it	defeat someone through trickery or deceit
loosen by turning	tighten or fasten by means of screwing motions
	cause to penetrate, as with a circular motion
	turn like a screw
	have sexual intercourse with