A spheroid is a shape close to a ball but not a true one — squashed a little flatter at two ends, or stretched a little longer, like an egg or a rugby ball. It is a noun, and mostly a maths, science and engineering word. The place students meet it most is geography: the Earth is called an oblate spheroid, meaning slightly flattened at the poles and slightly fatter at the equator, which is why maps and GPS calculations need it. Astronomers use it for planets and star clusters, doctors sometimes for the shape of a cell or a growth of cells, and engineers for a kind of cast iron. It can also work as an adjective (a spheroid body), though spheroidal is the more usual adjective. Two words you will see beside it: oblate (squashed, like a mandarin orange) and prolate (stretched, like an American football). In ordinary English nobody says this — they say egg-shaped, or oval, or "not quite round".

球狀體、扁球體（地理課上說地球是「扁球體」）