The term 'flattened at the poles' refers to a type of spheroid, which is an ellipsoid of revolution that is flattened at the poles. The crossword solution for this term is 'oblate, ' which means having a flattened shape at the poles. An oblate spheroid is a type of ellipsoid that is flattened at the poles and bulging at the equator. This shape is often seen in planets such as Earth, which is an oblate spheroid.