bunch up vs bunch

bunch up is not a noun while bunch is a noun.

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

As verbs, bunch up and bunch are synonyms defined as:

Other synonyms of bunch up include bunch together.

bunch up (noun)	bunch (noun)
	a grouping of a number of similar things
	an informal body of friends
	any collection in its entirety

bunch up (verb)	bunch (verb)
form into a bunch	gather or cause to gather into a cluster
	form into a bunch