radius

noun

(geometry) A line segment between any point of a circle or sphere and its center.

(geometry) The length of this line segment.

(anatomy) The long bone in the forearm, on the side of the thumb.

(zoology) The lighter bone (or fused portion of bone) in the forelimb of an animal.

Anything resembling a radius, such as the spoke of a wheel, the movable arm of a sextant, or one of the radiating lines of a spider's web.

(entomology) One of the major veins of the insect wing, between the subcosta and the media; the vein running along the costal edge of the discal cell.

(graph theory) The minimum eccentricity of any vertex, for a given graph.

(computing) Initialism of Remote Authentication Dial-In User Service.

verb

(transitive) To give a rounded edge to.

Roots

radiusradi- · Latin · ray, spoke

Synonyms for radius

diametern circumferencen widthn lengthn axisn circlen arean breadthn rangen

Synonyms & related words for radius

Find synonyms, related words, and the definition of radius — including diameter, circumference, width, length, axis, circle. Dendril is a free visual thesaurus that shows them on an interactive map where stronger matches sit closer to the center — no signup, no ads.

Words related to radius

Explore words related to radius — words associated with it, words that go with it, and its nearest matches in meaning. Related words include radii, interradial, radial, apothem, ulna, ulnae, perimeter, distances. Click any word to make it the center of the map and keep exploring the web of connections.

Synonyms for radius

Common synonyms for radius include diameter, circumference, width, length, axis, circle, area, breadth — words that share a close meaning. Hover or tap any word on the map for its definition and part of speech.

Where does radius come from?

The word radius breaks down into one root of Latin origin: the root radi-, from Latin radius (“ray, spoke”). Explore each root to see other English words built from the same source.