1.nounA curve on the surface of a cylinder or cone such that its angle to a plane perpendicular to the axis is constant; the three-dimensional curve seen in a screw or a spiral staircase.
2.nounA small volute under the abacus of a Corinthian capital.
3.nounThe incurved rim of the external ear.
4.nounAn upside down midair 360° spin in playboating.