effectivity vs effectiveness

effectivity and effectiveness both are nouns.

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

As nouns, effectivity and effectiveness are synonyms defined as:

effectivity and effectiveness: power to be effective; the quality of being able to bring about an effect

Other synonyms of effectivity include effectuality, effectualness.

effectivity (noun)	effectiveness (noun)
power to be effective; the quality of being able to bring about an effect	power to be effective; the quality of being able to bring about an effect
	capacity to produce strong physiological or chemical effects