mill about vs mill

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

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

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

Other synonyms of mill about include mill around.

mill about (noun)	mill (noun)
	the act of grinding to a powder or dust
	machinery that processes materials by grinding or crushing
	a plant consisting of one or more buildings with facilities for manufacturing

mill about (verb)	mill (verb)
move about in a confused manner	grind with a mill
be about a place without any apparent purpose	produce a ridge around the edge of
	roll out (metal) with a rolling machine
	move about in a confused manner