回转椭球

[ noun ]
a shape that is generated by rotating an ellipse around one of its axes
<noun.shape>
it looked like a sphere but on closer examination I saw it was really a spheroid

Ellipsoid \El*lip"soid\, n. [Ellipse + -oid: cf. F. ellipsoide.]
(Geom.)
A solid, all plane sections of which are ellipses or circles.
See {Conoid}, n., 2
(a) .

Note: The ellipsoid has three principal plane sections, a, b,
and c, each at right angles to the other two, and each
dividing the solid into two equal and symmetrical
parts. The lines of meeting of these principal sections
are the axes, or principal diameters of the ellipsoid.
The point where the three planes meet is the center.

{Ellipsoid of revolution}, a spheroid; a solid figure
generated by the revolution of an ellipse about one of its
axes. It is called a prolate spheroid, or prolatum, when
the ellipse is revolved about the major axis, and an
oblate spheroid, or oblatum, when it is revolved about the
minor axis.