efficacious vs effectivity

efficacious is not a noun while effectivity is a noun.

Word	Noun	Adjective	Verb	Adverb
efficacious	No	Yes	No	No
effectivity	Yes	No	No	No

efficacious (noun)	effectivity (noun)
	power to be effective; the quality of being able to bring about an effect

efficacious (adjective)	effectivity (adjective)
marked by qualities giving the power to produce an intended effect
producing or capable of producing an intended result or having a striking effect