Diametral

Part of speech: noun (n.)

A diameter. [Obs.] Sir T. Browne.

Part of speech: adjective (a.)

Pertaining to a diameter; diametrical. Diametral curve, Diametral surface (Geom.), any line or surface which bisects a system of parallel chords drawn in a curve or surface. -- Diametral planes (Crystal.), planes in which two of the axes lie.