A shape that is generated by rotating an ellipse around one of its axes:
— It looked like a sphere but on closer examination I saw it was really a spheroid.

synonym: ellipsoid of revolution.

Roget 249: rotundity; roundness etc. adj.; cylindricity^†; sphericity, spheroidity^†; globosity^†.    cylinder, cylindroid^†, cylindrical; barrel, drum; roll, roller; rouleau^†, column, rolling-pin, rundle.    cone, conoid^†; pear shape, egg shape, bell shape.    sphere, globe, ball, boulder, bowlder^†; spheroid, ellipsoid; oblong spheroid; oblate spheroid, prolate spheroid; drop, spherule, globule, vesicle, bulb, bullet, pellet, pelote^†, clew, pill, marble, pea, knob, pommel, horn; knot (convolution) 248.    curved surface, hypersphere; hyperdimensional surface.    ... show more

Polish: sferoida