dullness vs oscitancy

dullness and oscitancy both are nouns.

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

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

Other hyponyms of dullness include oscitance.

dullness (noun)	oscitancy (noun)
lack of sensibility	an involuntary intake of breath through a wide open mouth; usually triggered by fatigue or boredom
without sharpness or clearness of edge or point	drowsiness and dullness manifested by yawning
the quality of lacking interestingness
a lack of visual brightness
the quality of being slow to understand