perniciousness vs morbidity

perniciousness and morbidity both are nouns.

Word	Noun	Adjective	Verb	Adverb
perniciousness	Yes	No	No	No
morbidity	Yes	No	No	No

As nouns, morbidity is a hypernym of perniciousness; that is, morbidity is a word with a broader meaning than perniciousness:

Other hypernyms of perniciousness include morbidness, unwholesomeness.

perniciousness (noun)	morbidity (noun)
grave harmfulness or deadliness	the quality of being unhealthful and generally bad for you
	an abnormally gloomy or unhealthy state of mind
	the relative incidence of a particular disease