unstrap vs strap

unstrap is not a noun while strap is a noun.

Word	Noun	Adjective	Verb	Adverb
unstrap	No	No	Yes	No
strap	Yes	No	Yes	No

unstrap (noun)	strap (noun)
	whip consisting of a strip of leather used in flogging
	an elongated leather strip (or a strip of similar material) for binding things together or holding something in position
	a band that goes over the shoulder and supports a garment or bag
	hanger consisting of a loop of leather suspended from the ceiling of a bus or train; passengers hold onto it

unstrap (verb)	strap (verb)
remove the strap or straps from	secure (a sprained joint) with a strap
	sharpen with a strap
	tie with a strap
	beat severely with a whip or rod