radius

noun

ra·​di·​us ˈrā-dē-əs 

plural radii ˈrā-dē-ˌī  also radiuses

1

: a line segment extending from the center of a circle or sphere to the circumference or bounding surface

2

a

: the bone on the thumb side of the human forearm

also : a corresponding part of vertebrates above fishes

b

: the third and usually largest vein of an insect's wing

3

a

: the length of a radius

a truck with a short turning radius

b

: the circular area defined by a stated radius

c

: a bounded or circumscribed area

4

: a radial part

5

: the distance from a center line or point to an axis of rotation

Examples of radius in a Sentence

Measure the radius of the circle.

a radius of 10 inches

The new museum is expected to draw people from a wide radius.

There are three restaurants within a one-block radius of our apartment.

Recent Examples on the Web

Commuter towns will grow in locations in which housing and childcare is affordable and plentiful, which are safe from climate change, and increasingly, within a reachable radius of HQ. —Julia Hobsbawm, Fortune, 22 Apr. 2024

The hulking $55 million Monroe facility off Hamilton Lebanon Road in Butler County is powered by robots and was set up to process thousands of digital orders within a 90-mile radius – as far away as Dayton, Columbus, Indianapolis and Louisville. —Alexander Coolidge, The Enquirer, 21 Apr. 2024

That suggests a smaller turning radius for the Jeep, but Toyota did not allow on-road evaluation drives. —Mark Phelan, Detroit Free Press, 16 Apr. 2024

The agreement would settle all class-action claims within a 20-mile radius from the derailment, Norfolk Southern said in a statement announcing the deal, as well as personal injury claims within a 10-mile radius for residents who chose to participate. —Joel Rose, NPR, 9 Apr. 2024

Residents within a roughly 1-mile radius had to temporarily evacuate. —Minyvonne Burke, NBC News, 9 Apr. 2024

The company said Tuesday that the agreement, if approved by the court, will resolve all class action claims within a 20-mile radius from the derailment and, for those residents who choose to participate, personal injury claims within a 10-mile radius from the derailment. —CBS News, 9 Apr. 2024

Auto dealerships have restrictions that prevent them from being built within a 10-mile radius of one another, Riddell said. —Corina Vanek, The Arizona Republic, 8 Apr. 2024

And while there will be 16 TVs — including a giant screen — and room for 86 guests, Wheeler also loves the dense residential population with a half-mile radius of the restaurant’s location. —Jonathan Shikes, The Denver Post, 8 Apr. 2024

Word History

Etymology

Latin, ray, radius

First Known Use

1578, in the meaning defined at sense 1

Phrases Containing radius

• radius of curvature
• radius vector

Kids Definition

radius

noun

ra·​di·​us ˈrād-ē-əs 

plural radii -ē-ˌī  also radiuses

1

: the bone on the thumb side of the human forearm

also : a corresponding bone of other vertebrates

2

: a line extending from the center of a circle or sphere to the circumference or surface

3

a

: the length of a radius

b

: a circular area defined by a given radius

deer may wander within a radius of several miles

4

: a radial part or plane

Etymology

from Latin radius "ray, beam, spoke" — related to radiate, radio, ray entry 2

Medical Definition

radius

noun

ra·​di·​us ˈrād-ē-əs 

plural radii -ē-ˌī  also radiuses

: the bone on the thumb side of the human forearm or on the corresponding part of the forelimb of vertebrates above fishes that in humans is movably articulated with the ulna at both ends so as to permit partial rotation about that bone, that bears on its inner aspect somewhat distal to the head a prominence for the insertion of the biceps tendon, and that has the lower end broadened for articulation with the proximal bones of the carpus so that rotation of the radius involves also that of the hand