ellipsoidPronunciation: /ɪˈlɪpsɔɪd/Definition of ellipsoid noun a three-dimensional figure symmetrical about each of three perpendicular axes, whose plane sections normal to one axis are circles and all the other plane sections are ellipses. Derivatives ellipsoidalPronunciation: /ɛlɪpˈsɔɪd(ə)l/ adjective ellipsoid in other Oxford dictionaries Definition of ellipsoid in the US English dictionary