necessitate vs need

necessitate is not a noun while need is a noun.

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

As verbs, necessitate and need are synonyms defined as:

Other synonyms of necessitate include ask, call for, demand, involve, postulate, require, take.

necessitate (noun)	need (noun)
	the psychological feature that arouses an organism to action toward a desired goal; the reason for the action; that which gives purpose and direction to behavior
	anything that is necessary but lacking
	a condition requiring relief
	a state of extreme poverty or destitution

necessitate (verb)	need (verb)
require as useful, just, or proper	have need of
cause to be a concomitant	have or feel a need for
	require as useful, just, or proper