bum vs bum around

bum is a noun but bum around is not a noun.

Word	Noun	Adjective	Verb	Adverb
bum	Yes	Yes	Yes	No
bum around	No	No	Yes	No

As verbs, bum and bum around are synonyms defined as:

bum (noun)	bum around (noun)
the fleshy part of the human body that you sit on
a vagrant
a person who is deemed to be despicable or contemptible
person who does no work

bum (adjective)	bum around (adjective)
of very poor quality; flimsy

bum (verb)	bum around (verb)
ask for and get free; be a parasite	be lazy or idle
be lazy or idle