What does "radius" mean?
The long bone in the forearm, on the side of the thumb.
Radius
/ˈɹeɪ.di.əs/ noun, verb
noun, verb ·Common ·High school level
Meaning at a glance
- Primary sense: The long bone in the forearm, on the side of the thumb.
- Grammar: radius is listed as noun, verb.
- Nearest alternatives: air line, airline, ambit, amplitude.
- Useful contrasts: diameter, diameter measurement, diameters.
- Usage evidence: We deliver your order free of charge within a 20-mile radius.
How to use "radius"
- Start with the primary definition, then check the part of speech before placing the word in a sentence.
- Compare nearby synonyms to make sure "radius" carries the exact meaning, tone, and strength you need.
- Use the example sentence as a context check. If your sentence uses the word differently, confirm that the grammar still fits.
Meaning check
- Does the word fit the sentence's grammar?
- Does it match the intended tone rather than only the dictionary definition?
- Would a simpler synonym be clearer for the reader?
- Is there enough surrounding context to prevent ambiguity?
Source and review context
This entry combines structured lexical data with WordToolSet review checks. Definitions, examples, synonyms, and usage notes may come from different source tables, so the page is designed to show evidence from more than one angle before you rely on "radius" in a final draft.
If a word has several senses, prefer the sense that matches your sentence's grammar and surrounding context. A correct definition can still be the wrong choice when the sentence needs a different register, emphasis, or level of specificity.
Before you rely on this definition
Read the first definition as a starting point, then check the example, synonyms, and part of speech before treating "radius" as the right word for your sentence.
If your draft is formal, technical, persuasive, or sensitive, compare "radius" with a nearby alternative so the final choice matches both meaning and reader expectation.
Compare nearby meanings
- Use synonyms when you need a softer, stronger, simpler, or more specific word.
- Use antonyms to check the boundary of the meaning and avoid accidental contrast.
- Use the example sentence to confirm the word behaves naturally in context.
- Keep the original wording when a replacement adds complexity without improving precision.
Definition decision workflow
1. Identify the role
Check whether "radius" is acting as noun, verb in your sentence. A definition is only useful when the grammar matches the way the word is being used.
2. Test the nearest option
Compare it with "air line" and other nearby choices to see whether the sentence needs a softer, stronger, or more familiar word.
3. Confirm with context
Use the example sentence below as an evidence check, then read your own sentence out loud to catch tone or rhythm problems.
Review note: Definition pages are checked for source coverage, sentence evidence, synonym support, and editorial insight before they are treated as approval-ready pages. If the evidence is too thin, the page remains available to users but is kept out of the approval-facing indexed inventory.
Final meaning check
Before publishing a sentence with "radius", ask whether the word helps the reader understand the idea faster. A precise word should reduce confusion, not simply make the sentence look more polished.
When the definition, synonym evidence, and example context point in the same direction, the word is usually a safer choice. When they conflict, revise the sentence or choose a clearer alternative.
Definitions
Noun
- 1 The long bone in the forearm, on the side of the thumb.
"It is also obvious, and proved by experiment, that the rotatory motions observed in the hand proceed from the rotatory motions of the radius."
- 2 Initialism of Remote Authentication Dial-In User Service. abbreviation, alt-of, initialism, uncountable
- 3 support consisting of a radial member of a wheel joining the hub to the rim wordnet
- 4 The lighter bone (or fused portion of bone) in the forelimb of an animal.
- 5 the length of a line segment between the center and circumference of a circle or sphere wordnet
Show 8 more definitions
- 6 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.
- 7 the outer and slightly shorter of the two bones of the human forearm wordnet
- 8 A line segment between any point of a circle or sphere and its center.
"Fatima claims to have visited all the bars within a five-mile radius of her Manhattan apartment."
- 9 a circular region whose area is indicated by the length of its radius wordnet
- 10 The length of this line segment.
"This contribution reduces with increasing distance p from the emitting surface element dA, due to conservation of energy, as the wave energy distributed across the spherical wave front remains constant, while the radius increases during ..."
- 11 a straight line from the center to the perimeter of a circle (or from the center to the surface of a sphere) wordnet
- 12 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.
"[…] I can do more with a Quadrant, Sextant or Octant, of 1 foot Radius, furniſhed with Teleſcopical Sights and Screws, then ^([sic]) can poſſibly be done with any other Inſtrument, furniſhed only with Common Sights, though 10, 20, 30, nay threeſcore foot Radius; […]"
- 13 The minimum eccentricity of any vertex, for a given graph.
Verb
- 1 To give a rounded edge to. transitive
"A comfortable grip is ensured by smoothing the surface of the handle and radiusing the edge."
Synonyms
All synonymsExample
"We deliver your order free of charge within a 20-mile radius."
Common questions
What is a synonym for "radius"?
Common synonyms include: air line, airline, ambit, amplitude, annular muscle, annulus.
How do you use "radius" in a sentence?
We deliver your order free of charge within a 20-mile radius.
How do you pronounce "radius"?
Pronounced /ˈɹeɪ.di.əs/.
Etymology
Borrowed from Latin radius (“ray”). Doublet of ray.