Ellipsograph :: Ellipsograph (n.) An instrument for describing ellipses; -- called also trammel.
Ellipsoid :: Ellipsoid (n.) A solid, all plane sections of which are ellipses or circles. See Conoid, n., 2 (a)..
Ellipsoidal :: Ellipsoidal (a.) Pertaining to, or shaped like, an ellipsoid; as, ellipsoid or ellipsoidal form..