windmill vs grinder

windmill and grinder both are nouns.

Word	Noun	Adjective	Verb	Adverb
windmill	Yes	No	No	No
grinder	Yes	No	No	No

As nouns, grinder is a hypernym of windmill; that is, grinder is a word with a broader meaning than windmill:

Other hypernyms of windmill include mill, milling machinery.

windmill (noun)	grinder (noun)
generator that extracts usable energy from winds	a machine tool that polishes metal
a mill that is powered by the wind	machinery that processes materials by grinding or crushing
	grinding tooth with a broad crown; located behind the premolars
	a large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States