Diameter

1. (Geom.) The distance through the lower part of the shaft of a column, used as a standard measure for all parts of the order. See Module.
1. Any right line passing through the center of a figure or body, as a circle, conic section, sphere, cube, etc., and terminated by the opposite boundaries; a straight line which bisects a system of parallel chords drawn in a curve.
2. A diametral plane.
Conjugate diameters .
See under Conjugate.