mill about vs lounge

mill about is not a noun while lounge is a noun.

Word	Noun	Adjective	Verb	Adverb
mill about	No	No	Yes	No
lounge	Yes	No	Yes	No

As verbs, mill about and lounge are synonyms defined as:

Other synonyms of mill about include footle, hang around, lallygag, linger, loaf, loiter, lollygag, lurk, mess about, mill around, tarry.

mill about (noun)	lounge (noun)
	a room (as in a hotel or airport) with seating where people can wait
	an upholstered seat for more than one person

mill about (verb)	lounge (verb)
move about in a confused manner	sit or recline comfortably
be about a place without any apparent purpose	be about a place without any apparent purpose