eccentricity vs oddness

eccentricity and oddness both are nouns.

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

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

Other hyponyms of eccentricity include oddity.

eccentricity (noun)	oddness (noun)
strange and unconventional behavior	eccentricity that is not easily explained
a circularity that has a different center or deviates from a circular path	the parity of odd numbers (not divisible by two)
(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