hardening vs callosity

hardening and callosity both are nouns.

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

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

hardening: abnormal hardening or thickening of tissue
callosity: an area of skin that is thick or hard from continual pressure or friction (as the sole of the foot)

Other hyponyms of hardening include callus, calcification.

hardening (noun)	callosity (noun)
the act of making something harder (firmer or tighter or more compact)	devoid of passion or feeling; hardheartedness
the process of becoming hard or solid by cooling or drying or crystallization	an area of skin that is thick or hard from continual pressure or friction (as the sole of the foot)
abnormal hardening or thickening of tissue