diametrical

American  

[dahy-uh-me-tri-kuhl] / ˌdaɪ əˈmɛ trɪ kəl /

Also diametric

adjective

1. of, relating to, or along a diameter.

2. in direct opposition; being at opposite extremes; complete.

   diametrical opposites; a diametrical difference.

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Other Word Forms

• diametrically adverb
• undiametric adjective
• undiametrical adjective
• undiametrically adverb

Etymology

Origin of diametrical

1545–55; < Greek diametrik ( ós ) ( diámetr ( os ) diameter + -ikos -ic ) + -al ¹

Explanation

In geometry, the adjective diametrical has to do with a straight line running through the middle of a circle — all diametrical lines will intersect at the very center. Aside from its mathematical meaning, you an also use this word to emphasize how opposed two things (or people) are. If you and your sister couldn't possibly be more different (she's a morning person, while you're a night owl; she's outgoing, you're an introvert), you can say you're diametrical opposites. The root of diametrical is the Greek diametros, "diagonal of a circle."

Example Sentences

He’s the proto-incel, and the diametrical opposite to Garfield, whom Makowsky defines as “lawful good,” to borrow the Dungeons & Dragons classification.

From Los Angeles Times • Nov. 6, 2025

And though the two movies look like diametrical opposites, they share a pair of undeniable throughlines: the aching, all-consuming feeling of desire and the remarkable actors chosen to depict it.

From Salon • Nov. 27, 2024

The diametrical pair overtook Holmes in the primary.

From Seattle Times • Feb. 6, 2022

But van Eyck’s “Crucifixion” and “Last Judgment” panels, on view at the Metropolitan Museum of Art in New York, take this diametrical effect to an astonishing level of visual intensity.

From Washington Post • Oct. 14, 2020

For a creature of its size and power for mischief there is no living thing more easy to kill or disable than an ostrich, wherein again comes another diametrical difference.

From Aletta A Tale of the Boer Invasion by Mitford, Bertram