mess around vs muck about

mess around and muck about both are verbs.

Word	Noun	Adjective	Verb	Adverb
mess around	No	No	Yes	No
muck about	No	No	Yes	No

As verbs, mess around and muck about are synonyms defined as:

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

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

mess around (verb)	muck about (verb)
do random, unplanned work or activities or spend time idly	do random, unplanned work or activities or spend time idly