ponderosity vs heaviness

ponderosity and heaviness both are nouns.

Word	Noun	Adjective	Verb	Adverb
ponderosity	Yes	No	No	No
heaviness	Yes	No	No	No

As nouns, heaviness is a hypernym of ponderosity; that is, heaviness is a word with a broader meaning than ponderosity:

Other hypernyms of ponderosity include weightiness.

ponderosity (noun)	heaviness (noun)
the property of being large in mass	the property of being comparatively great in weight
	used of a line or mark
	unwelcome burdensome difficulty
	an oppressive quality that is laborious and solemn and lacks grace or fluency
	persisting sadness