Spheroid

A spheroid is a "squashed sphere"

Try different styles in this animation here:

A spheroid can be made by taking an ellipse and rotating it about its minor or major axis. Press play to see:

Oblate vs Prolate

The flatter one is oblate, the taller one is prolate (think "prolonged"):

Here are some more examples:

A watermelon is like a prolate spheroid

A discus is like an oblate spheroid

Planet Earth, our home, is squashed a little at the poles,
making it an oblate spheroid, but a very mild version of one.

Ellipsoid

An ellipsoid is the more general case of a spheroid.

• A spheroid is a specific type of ellipsoid that's symmetric about its polar axis (like a squashed or stretched sphere)
• An ellipsoid is the general 3D shape where all three perpendicular axes can have different lengths