oddity vs eccentricity

oddity and eccentricity both are nouns.

Word	Noun	Adjective	Verb	Adverb
oddity	Yes	No	No	No
eccentricity	Yes	No	No	No

As nouns, eccentricity is a hypernym of oddity; that is, eccentricity is a word with a broader meaning than oddity:

oddity (noun)	eccentricity (noun)
something unusual -- perhaps worthy of collecting	strange and unconventional behavior
a strange attitude or habit	a circularity that has a different center or deviates from a circular path
eccentricity that is not easily explained	(geometry) a ratio describing the shape of a conic section; the ratio of the distance between the foci to the length of the major axis