callosity vs dullness

callosity and dullness both are nouns.

Word	Noun	Adjective	Verb	Adverb
callosity	Yes	No	No	No
dullness	Yes	No	No	No

As nouns, dullness is a hyponym of callosity; that is, dullness is a word with a more specific, narrower meaning than callosity:

callosity (noun)	dullness (noun)
devoid of passion or feeling; hardheartedness	lack of sensibility
an area of skin that is thick or hard from continual pressure or friction (as the sole of the foot)	without sharpness or clearness of edge or point
	the quality of lacking interestingness
	a lack of visual brightness
	the quality of being slow to understand