ponderous vs ponderousness

ponderous is not a noun while ponderousness is a noun.

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

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

ponderous (adjective)	ponderousness (adjective)
slow and laborious because of weight
having great mass and weight and unwieldiness
labored and dull