What is a section or part of a cylinder, cone, or other solid of revolution, cut off by a plane oblique to the base; -- so called from its resemblance to the hoof of a horse called?

ungula — (Geom.) A section or part of a cylinder, cone, or other solid of revolution, cut off by a plane oblique to the base; -- so called from its resemblance to the hoof of a horse. (Webster's 1913.)

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