What does diametrically mean?
"Diametrically" is a formal adverb meaning completely or utterly, most often used to stress that two things are direct opposites. Its signature construction is the phrase "diametrically opposed," which describes positions, beliefs, personalities, or interpretations that stand as far apart as possible — like two points on opposite ends of a circle's diameter. The word carries an air of precision and finality: when views are said to be diametrically opposed, no middle ground is implied. Beyond this figurative use, it retains a literal geometric sense, describing something positioned along a diameter of a circle or sphere, though this appears mainly in mathematical or scientific writing. Derived from Greek roots meaning "measure across," the word entered English via Latin in the early modern period. It is a valuable tool for writers who want to convey total opposition with elegance and authority, and it pairs naturally with words such as "opposite" and "contrary."
adverbIn a way that is completely opposed or directly opposite; entirely. Also, with reference to geometry, along a diameter.
- Completely; utterly — used especially in the phrase 'diametrically opposed', meaning at opposite extremes.
- (Geometry) Along a diameter of a circle or sphere.
"The two brothers held diametrically opposed views on politics."
"Their accounts of the accident were diametrically opposed."
"The two points on the sphere lie diametrically across from each other."
"Diametrically" comes from the Greek for "across a diameter" — so two diametrically opposed ideas sit as far apart as the opposite points on a circle's edge.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of diametrically
"Diametrically" derives from "diametric," which traces back through Late Latin "diametralis" to Greek "diametros" (διάμετρος), from "dia-" meaning "across, through" and "metron" meaning "measure." The Greek term originally described the straight line measuring across a circle through its center. The adverb entered English in the late 16th to early 17th century, initially in its literal geometric sense before developing its figurative sense of complete opposition. Cognates sharing the same Greek root include "diameter," "perimeter," and "metric."
Related word forms
How diametrically is actually used
Formal to neutral register. In modern usage it almost always appears before 'opposed' or 'opposite'; standalone use is rare outside technical (geometric) contexts. Common in academic writing, journalism, and formal argument.
Easily confused with diametrically
'Diabolically' means in an extremely wicked or devilish manner, while 'diametrically' means completely or directly opposite.