The Collaborative International Dictionary of English v.0.48:
Oblateness \Ob*late"ness\, n. The quality or state of being oblate. [1913 Webster]WordNet (r) 3.0 (2006):
oblateness n 1: the property possessed by a round shape that is flattened at the poles; "the oblateness of the planet" [syn: oblateness, ellipticity]