massiveness vs ponderosity

massiveness and ponderosity both are nouns.

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

As nouns, massiveness and ponderosity are synonyms defined as:

Other synonyms of massiveness include heft, heftiness, ponderousness.

massiveness (noun)	ponderosity (noun)
an unwieldy largeness	the property of being large in mass
the property of being large in mass