回かい転てん楕だ円えん体たい

noun

spheroid

A mathematical term for a quadric surface obtained by rotating an ellipse about one of its principal axes; used in geometry, physics, and geodesy.

• 地ち球きゅうは完かん全ぜんな球きゅうではなく、回かい転てん楕だ円えん体たいに近ちかい形かたちをしている。

  The Earth is not a perfect sphere but has a shape close to a spheroid.