water mill vs mill

water mill and mill both are nouns.

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

As nouns, mill is a hypernym of water mill; that is, mill is a word with a broader meaning than water mill:

Other hypernyms of water mill include grinder, milling machinery.

water mill (noun)	mill (noun)
a mill powered by a water wheel	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

water mill (verb)	mill (verb)
	grind with a mill
	produce a ridge around the edge of
	roll out (metal) with a rolling machine
	move about in a confused manner