Diametrical

Diametrical is an adjective used in both technical and figurative contexts. In geometry, it pertains to a diameter, the line segment that passes through the center of a circle or sphere and connects two boundary points. Two points on a circle are diametrically opposite if they lie at the endpoints of a common diameter; the central angle between them is 180 degrees. On a sphere, diametrally opposite points, often called antipodal points, are connected by a diameter through the center.

In general usage, diametrical describes complete opposition or contrast, such as diametrically opposed viewpoints or opinions. This sense emphasizes absolute difference rather than gradual disagreement.

Etymology and spelling: The term derives from Latin diametricus, from Greek diametros meaning “diameter,” formed from dia- “through” and metron “measure.” The spellings diametric and diametrical are both standard, with diametrical often preferred when emphasizing the diameter-related sense and diametric more common in broader or figurative usage.

Related terms include diameter, diametrical opposite, and antipodal. In geometry, diametrical opposite points lie on the same diameter of a circle or sphere and are mirror images across the center. In everyday language, the phrase diametrically opposed is used to indicate complete opposition in position, belief, or approach.