Real Dictionary

ellipsoid in American English
a solid formed by rotating an ellipse around either axis: its plane sections are all ellipses or circles
of or shaped like an ellipsoid
adjective: pertaining to or having the form of an ellipsoid; ellipsoidal
noun: a solid figure all plane sections of which are ellipses or circles. Typical equation: (x2/a2) + (y2/b2) + (z2/c2) = 1

ellipsoid in British English
noun: a geometric surface, symmetrical about the three coordinate axes, whose plane sections are ellipses or circles. Standard equation: x2/a2 + y2/ b2 + z2/ c2 = 1, where ±a, ±b, ±c are the intercepts on the x-, y-, and z- axes