diametral

Diametral is an adjective meaning relating to or measured along a diameter. The term comes from Latin diametralis, ultimately from Greek di- “through” and metron “measure.” It is used primarily in geometry and disciplines that employ the concept of a diameter.

In circle geometry, a diameter is a straight line that passes through the center of the circle and has its endpoints on the circle. Diametral concepts include diametral opposite points, which are the endpoints of a diameter. The distance between any two points on a circle is at most the circle’s diameter, with equality occurring for diametral opposites.

In three-dimensional contexts, a diametral plane is any plane that passes through the center of a sphere. The intersection of such a plane with the sphere is a great circle, and the plane divides the sphere into two congruent halves.

In metric and convex geometry, the diameter of a set is the greatest distance between any two points in the set. Points that realize this maximum are called diametral points. The term diametral distance likewise describes this maximal separation.

Beyond pure geometry, diametral is used in various technical fields to describe relations or measurements tied to a diameter or centered symmetry, such as assessments of width, alignment, or cross-sections through a central point. While context-specific, diametral consistently conveys the idea of through- or across-a-center measurements.

---