ellipticity vs oblateness

ellipticity and oblateness both are nouns.

Word	Noun	Adjective	Verb	Adverb
ellipticity	Yes	No	No	No
oblateness	Yes	No	No	No

As nouns, ellipticity and oblateness are synonyms defined as:

ellipticity and oblateness: the property possessed by a round shape that is flattened at the poles

ellipticity (noun)	oblateness (noun)
the property possessed by a round shape that is flattened at the poles	the property possessed by a round shape that is flattened at the poles