ponderousness vs massiveness

ponderousness and massiveness both are nouns.

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

As nouns, ponderousness and massiveness are synonyms defined as:

Other synonyms of ponderousness include heft, heftiness, ponderosity.

ponderousness (noun)	massiveness (noun)
the property of being large in mass	an unwieldy largeness
an oppressive quality that is laborious and solemn and lacks grace or fluency	the property of being large in mass