modify vs grammar

modify is not a noun while grammar is a noun.

Word	Noun	Adjective	Verb	Adverb
modify	No	No	Yes	No
grammar	Yes	No	No	No

modify (noun)	grammar (noun)
	the branch of linguistics that deals with syntax and morphology (and sometimes also deals with semantics)

modify (verb)	grammar (verb)
make less severe or harsh or extreme
add a modifier to a constituent
cause to change; make different; cause a transformation