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 Ideally, the driver is looking for a parking spot with a 5-minute walk to the theater (~400m radius). Sabbir Rangwala, Forbes, 9 Oct. 2024 Second, Tampa Bay creates a large funnel — particularly for a hurricane with its radius of maximum winds near the mouth of the bay, the report said. Doyle Rice, USA TODAY, 7 Oct. 2024 The weapon’s blast, or lethal fragmentation radius – an area of exposure to injury or death around the target – is up to 365 meters (about 1,198 feet), or the equivalent of 58 soccer fields. Allegra Goodwin, CNN, 30 Sep. 2024 Sun High grows dwarf trees in their orchards with a generous picking radius, another subtle attention to detail. Kat Chen, Condé Nast Traveler, 18 Sep. 2024 See all Example Sentences for radius 

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 5 Nov. 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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