Ellipsoid is a family of surfaces that can be described by this equation:

ellipsoid 34mDg
a = 2; b = 1.5; c = 1;
ParametricPlot3D[{a*Cos[u]*Sin[v], b*Sin[u]*Sin[v], c*Cos[v]}, {u, 0, Pi}, {v, 0, 2*Pi},
  Axes -> False, Boxed -> False, BoundaryStyle -> {Thin, Black},
  PlotStyle -> Directive[RandomColor[], Opacity[0.7], Specularity[White, 30]]]

It is called ellipsoid because the cross section alone the axes of the surface are ellipses, and the equation's form is the 3D analogue of the equation for ellipses.

Conic Section Surfaces