jejunity vs dullness

jejunity and dullness both are nouns.

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

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

jejunity (noun)	dullness (noun)
the quality of being vapid and unsophisticated	lack of sensibility
quality of inadequate nutritive value	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