undo vs undoing

undo is not a noun while undoing is a noun.

Word	Noun	Adjective	Verb	Adverb
undo	No	No	Yes	No
undoing	Yes	No	No	No

undo (noun)	undoing (noun)
	an act that makes a previous act of no effect (as if not done)
	loosening the ties that fasten something

undo (verb)	undoing (verb)
cancel, annul, or reverse an action or its effect
cause to become loose
remove the outer cover or wrapping of
deprive of certain characteristics
cause the ruin or downfall of