make unnecessary vs prevent

make unnecessary and prevent both are verbs.

Word	Noun	Adjective	Verb	Adverb
make unnecessary	No	No	Yes	No
prevent	No	No	Yes	No

As verbs, prevent is a hypernym of make unnecessary; that is, prevent is a word with a broader meaning than make unnecessary:

Other hypernyms of make unnecessary include forbid, foreclose, forestall, preclude.

make unnecessary (verb)	prevent (verb)
make unnecessary an expenditure or effort	stop (someone or something) from doing something or being in a certain state
	keep from happening or arising; make impossible