n. 直径

[医] 直经, 径

Diameter \Di*am"e*ter\, n. [F. diam[`e]tre, L. diametros, fr.
Gr. ?; dia` through + ? measure. See {Meter}.]
1. (Geom.)
(a) 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.
(b) A diametral plane.

2. 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.

Note: In an elongated object the diameter is usually taken at
right angles to the longer axis.

3. (Arch.) 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}.

{Conjugate diameters}. See under {Conjugate}.