putter vs mess around

putter is a noun but mess around is not a noun.

Word	Noun	Adjective	Verb	Adverb
putter	Yes	No	Yes	No
mess around	No	No	Yes	No

As verbs, putter and mess around are synonyms defined as:

putter and mess around: do random, unplanned work or activities or spend time idly

Other synonyms of putter include monkey, monkey around, muck about, muck around, potter, tinker.

putter (noun)	mess around (noun)
the iron normally used on the putting green
a golfer who is putting

putter (verb)	mess around (verb)
move around aimlessly	do random, unplanned work or activities or spend time idly
do random, unplanned work or activities or spend time idly
work lightly