add vs additive

add is not a noun while additive is a noun.

Word	Noun	Adjective	Verb	Adverb
add	No	No	Yes	No
additive	Yes	Yes	No	No

add (noun)	additive (noun)
	something added to enhance food or gasoline or paint or medicine

add (adjective)	additive (adjective)
	characterized or produced by addition
	designating or involving an equation whose terms are of the first degree

add (verb)	additive (verb)
make an addition (to); join or combine or unite with others; increase the quality, quantity, size or scope of
make an addition by combining numbers
determine the sum of
state or say further
bestow a quality on
constitute an addition