1. In geometry, a solid formed by the revolution of a conic section about its axis. If the conic section is a parabola, the resulting solid is a parabolic conoid, or paraboloid; if a hyperbola, the solid is a hyperbolic conoid, or hyperboloid; of an ellipse, an elliptic conoid, a spheroid, or an ellipsoid.

2. In anatomy, a gland in the third ventricle of the brain, resembling a cone or pine-apple, and called the pineal gland.