radius

noun

ra·​di·​us ˈrā-dē-əs How to pronounce radius (audio)
plural radii ˈrā-dē-ˌī How to pronounce radius (audio) 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 The airport in the United Arab Emirates, which is focused on making the airport an experience in itself, took the top spot mostly due to the more than 70 luxury hotels within a three-mile radius of the terminal. Alison Fox, Travel + Leisure, 6 Mar. 2024 Between 2012 and the end of 2022, there were two fatal crashes on X Street within a two-block radius of the collision that killed Johnston. Ariane Lange, Sacramento Bee, 6 Mar. 2024 That there were scores of capable actors within a five mile radius of the Geffen Playhouse (Ullett among them) hardly mattered. Charles McNulty, Los Angeles Times, 4 Mar. 2024 Kendra Scott stores within a five-mile radius of one of the Target locations experienced a 45% increase in sales over the following 12 weeks and its e-commerce business jumped 25% as well. Pamela N. Danziger, Forbes, 2 Mar. 2024 The one-minute tracking rule was designed to resolve that blind spot, by aiming to nail down a crash site to within a radius of six nautical miles. Tribune News Service, The Mercury News, 26 Feb. 2024 The Braves use both on-site parking spots and pre-existing spots within a one-mile radius for their 41,000-seat stadium. Joseph Hernandez, Kansas City Star, 24 Feb. 2024 City officials promised the $432 million would come from a new tax on properties within a two-mile radius of the arena. Laura Vozzella, Washington Post, 17 Feb. 2024 It is based on a decentralized urban planning model in which all residents' needs are met within a 15-minute radius, regardless of the mode of transport used (on foot, by bike, by public transport). Arnaud Devigne, Forbes, 21 Feb. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'radius.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Latin, ray, radius

First Known Use

1578, in the meaning defined at sense 1

Time Traveler
The first known use of radius was in 1578

Dictionary Entries Near radius

Cite this Entry

“Radius.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radius. Accessed 19 Mar. 2024.

Kids Definition

radius

noun
ra·​di·​us ˈrād-ē-əs How to pronounce radius (audio)
plural radii -ē-ˌī How to pronounce radius (audio) 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 How to pronounce radius (audio)
plural radii -ē-ˌī How to pronounce radius (audio) 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
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