PROLATE

, or Oblong Spberoid, is a spheroid produced by the revolution of a semiellipsis about its longer diameter; being longest in the direction of that axis, and resembling an egg, or a lemon.

It is so called in opposition to the oblate or short spheroid, which is formed by the rotation of a semiellipsis about its shorter axis; being therefore shortest in the direction of its axis, or flatted at the poles, and so resembling an orange, or perhaps a turnip, according to the degree of flatness; and which is also the figure of the earth we inhabit, and perhaps of the planets also; having their equatorial diameter longer than the polar. See Spheroid.