necessitate vs cost

necessitate is not a noun while cost is a noun.

Word	Noun	Adjective	Verb	Adverb
necessitate	No	No	Yes	No
cost	Yes	No	Yes	No

As verbs, cost is a hyponym of necessitate; that is, cost is a word with a more specific, narrower meaning than necessitate:

Other hyponyms of necessitate include claim, exact, take, govern, draw, cry for, cry out for, compel.

necessitate (noun)	cost (noun)
	the property of having material worth (often indicated by the amount of money something would bring if sold)
	value measured by what must be given or done or undergone to obtain something
	the total spent for goods or services including money and time and labor

necessitate (verb)	cost (verb)
require as useful, just, or proper	be priced at
cause to be a concomitant	require to lose, suffer, or sacrifice