in geometry, a solid body generated by the revolution of some curve line about its base or double ordinate; in opposition to a conoid, which is generated by the rotation of the curve about its axis or absciss, perpendicular to its ordinate. The spindle is denominated circular, elliptic, hyperbolic, or parabolic, &c. according to the figure of its generating curve.

in mechanics, sometimes denotes the axis of a wheel, or roller, &c. and its ends are the pivots.