radius

/ˈɹeɪ.di.əs/

//ˈɹeɪ.di.əs// noun

By · According to Wiktionary data (CC BY-SA) ·

"radius" is a 6-letter English headword indexed on PlainSpell.

The verdict

“radius” has 8 generated spelling variants in the English index at frequency #8,847. The variants make it a useful spelling check.

#8,847
frequency rank, English
3,094
“R” headwords
8
tracked misspellings
7
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - The long bone in the forearm, on the side of the thumb.

Corpus desk

Index EN-radius · radius · English

radius · rank #8,847 · 8 variants · 7 confusables

  • FREQ-COMMON #8,847
  • LEN-LONG 6 letters
  • VOW-3 3 vowels
  • CONFUS-MID 7 pairs
  • VAR-MID 8 variants
  • BOOK-MID 3,094
  • PHOTO-FINISH quantities

Nearest frequency peer: quantities (-1 rank slots)

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Frequency neighbourhood for “radius”

Lower corpus rank = more everyday usage (inverted bar length for readability)

corpus weight

What this shows Bars show where “radius” sits against the nearest ranked English headwords in the FrequencyWords band, not a reprint of letter-browse containment.

Source FrequencyWords open word-frequency list As of September 3, 2026

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

radius vs rains
67% similar
radius vs rails
67% similar
radius vs radio
67% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for radius
PropertyValue
Headwordradius
LanguageEnglish
Part of speechNoun
IPA/ˈɹeɪ.di.əs/
Letters6
Frequency rank#8,847
Misspellings tracked8
Confusable pairs7
SourceWiktionary (kaikki.org)

Where “radius” sits in English frequency

Every-word frequency runs from the handful of words we use constantly (left) to the long tail used once in a blue moon (right).radius lands here:

#1#100#1K#10K#100K
← used constantlyrarely used →

The axis is logarithmic, with each marked tick roughly ten times rarer than the last. Source: FrequencyWords open word-frequency list.

A misspelling magnet

The generator records 8 spelling variants around radius (IPA /ˈɹeɪ.di.əs/), anoun. Corpus frequency is #8,847 among 3,094 “R” headwords. Wiktionary lists 7 senses, so context still picks the gloss.

Our generated misspelling index lists 8 likely wrong-spelling variants for radius, with forms such as "ardius", "raddius", and "radisu". Every one of these variants traces to a single-character edit -- an added or dropped letter, a swapped consonant, or a vowel swap -- the kind of slip a spell-checker is built to catch. It also participates in 7 confusable-pair relationships, "rains", "rails", "radio", and more, where similar look or sound leads writers to substitute one word for another in context.

Etymologically, the entry records: Borrowed from Latin radius (“ray”). Doublet of ray. The correct English form is radius, spelled R-A-D-I-U-S.

Definition

  1. 1
    The long bone in the forearm, on the side of the thumb.
  2. 2
    The lighter bone (or fused portion of bone) in the forelimb of an animal.
  3. 3
    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.
  4. 4
    A line segment between any point of a circle or sphere and its center.
  5. 5
    The length of this line segment.
  6. 6
    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.
  7. 7
    The minimum eccentricity of any vertex, for a given graph.

Recorded use

Wiktionary examples

These source excerpts show how radius appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. 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. Fatima claims to have visited all the bars within a five-mile radius of her Manhattan apartment.

Etymology

Borrowed from Latin radius (“ray”). Doublet of ray.

Synonyms

R

This word in other languages

radio(Español)radius(Français)Speiche(Deutsch)rádio(Português)

Common misspellings

Also misspelled as:

  • ardius
  • raddius
  • radisu
  • radiuss
  • raduis
  • raidus
  • rdaius
  • rradius

Misspelling Pattern Breakdown

How far each generated variant is from the correct spelling of radius - measured in single-character edits (insert, delete, or substitute a letter). Larger bars are easier to catch; one-edit slips are the sneakiest.

ardius2raddius1radisu2radiuss1raduis2raidus2rdaius2rradius1
Edit distance from "radius"

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

PlainSpell is rendered directly from structured Wiktionary extracts and open word-frequency lists, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of September 3, 2026. Primary sources: Wiktionary (via kaikki.org) and FrequencyWords.

Frequently Asked Questions

How do you spell "radius"?
"radius" is spelled R-A-D-I-U-S. The IPA pronunciation is /ˈɹeɪ.di.əs/.
What does "radius" mean?
As a noun, "radius" means: The long bone in the forearm, on the side of the thumb.
What words are commonly confused with "radius"?
"radius" is commonly confused with "rains", "rails", "radio". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "radius"?
The IPA (International Phonetic Alphabet) transcription for "radius" is /ˈɹeɪ.di.əs/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "radius"?
Borrowed from Latin radius (“ray”). Doublet of ray. See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "radius", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 6 letters (nearest by frequency rank).

prompt#8,845pickup#8,841scroll#8,854Panama#8,839

Similar misspelling depth

Headwords with a similar count of attested misspellings (8 here; floor ≥5).

stunt8 variantsManuel8 variantslegion8 variantsjumps8 variants

What to do next

You've looked up "radius". Here's where to go from here.

  • "radius" maps to 7 confusable pairs in this vintage; the highest-scored is "rains". View pair
  • 8 edit-distance misspelling variants are generated for spell-check research on this headword. See variants
  • Usage frequency rank #8,847 among English headwords in this corpus. Corpus statistics
  • Browse more English words in the "R" letter cohort. R–Z browse
  • PlainSpell rotates a curated Word of the Day from the English corpus, a passive way to discover vocabulary. Word of the Day

PlainSpell is a reference corpus, not spelling advice. Verify unusual forms in context.

Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list