Deviation from perfect circular or spherical form toward elliptic or ellipsoidal form.(noun)
The degree of this deviation.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "ellipticity" in a sentence
"AFAIU the ellipticity of an egg is due to the pressures from the surrounding egg canal in which it is transported in during its assembly."
"He granted that the proposition connected mathematically the inverse square law to the ellipticity of the course of the planets."
"(Sometimes circularity is called or confused with ellipticity, but I prefer the former.)"