oscitancy vs dullness

oscitancy and dullness both are nouns.

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

As nouns, dullness is a hypernym of oscitancy; that is, dullness is a word with a broader meaning than oscitancy:

Other hypernyms of oscitancy include obtuseness, drowsiness, sleepiness, somnolence.

oscitancy (noun)	dullness (noun)
an involuntary intake of breath through a wide open mouth; usually triggered by fatigue or boredom	lack of sensibility
drowsiness and dullness manifested by yawning	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