radius

Reading level: hard

Estimated CEFR level: C2 — Proficiency

Estimated from word frequency; not an official CEFR classification.

Definition

noun the length of a line segment between the center and circumference of a circle or sphere
noun a straight line from the center to the perimeter of a circle (or from the center to the surface of a sphere)
noun a circular region whose area is indicated by the length of its radius

Borrowed from Latin radius (“ray”). Doublet of ray.

No land appeared within a radius of fifty miles. — The Mysterious Island, Jules Verne
She came forward within the radius of the light. — The Gay Cockade, Temple Bailey
REACH, n. The radius of action of the human hand. — The Devil's Dictionary, Ambrose Bierce

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