Diameter :: Diameter (n.) 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..
Diameter :: Diameter (n.) The length of a straight line through the center of an object from side to side; width; thickness; as, the diameter of a tree or rock..
Diameter :: Diameter (n.) 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..
Semidiameter :: Semidiameter (n.) Half of a diameter; a right line, or the length of a right line, drawn from the center of a circle, a sphere, or other curved figure, to its circumference or periphery; a radius..