Standard Lemma guide

radius

noun · verb · 14 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.

  • rā'-dē-əs
  • /ˈɹeɪ.di.əs/
  • US: Recorded audio is listed in the source snapshot.
  • rhymes with -eɪdiəs
  • CMU ARPABET: R EY1 D IY0 AH0 S Digits mark lexical stress: 1 primary, 2 secondary, 0 unstressed.

1

noun

Meaning 1

The long bone in the forearm, on the side of the thumb.

Definition source: English Wiktionary via Wiktextract

Topics: anatomy, medicine, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

The lighter bone (or fused portion of bone) in the forelimb of an animal.

Definition source: English Wiktionary via Wiktextract

Topics: biology, natural-sciences, zoology

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

3

noun

Meaning 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.

Definition source: English Wiktionary via Wiktextract

Topics: biology, entomology, natural-sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

4

noun

Meaning 4

A line segment between any point of a circle or sphere and its center.

Definition source: English Wiktionary via Wiktextract

Topics: geometry, mathematics, sciences

Examples

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

Meaning relationships

Synonyms: none provided

Antonyms: none provided

5

noun

Meaning 5

The length of this line segment.

Definition source: English Wiktionary via Wiktextract

Topics: geometry, mathematics, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

6

noun

Meaning 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.

Definition source: English Wiktionary via Wiktextract

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

7

noun

Meaning 7

The minimum eccentricity of any vertex, for a given graph.

Definition source: English Wiktionary via Wiktextract

Topics: graph-theory, mathematics, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

8

noun

Meaning 8

Initialism of Remote Authentication Dial-In User Service.

Definition source: English Wiktionary via Wiktextract

Usage: abbreviation, alt-of, initialism, uncountable

Topics: computing, engineering, mathematics, natural-sciences, physical-sciences, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

9

verb

Meaning 9

To give a rounded edge to.

Definition source: English Wiktionary via Wiktextract

Usage: transitive

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

10

noun

Meaning 10

support consisting of a radial member of a wheel joining the hub to the rim

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: spoke, wheel spoke

Antonyms: none provided

Broader terms: support

11

noun

Meaning 11

the length of a line segment between the center and circumference of a circle or sphere

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: r

Antonyms: none provided

Broader terms: length

Narrower terms: semidiameter, radius of curvature

12

noun

Meaning 12

the outer and slightly shorter of the two bones of the human forearm

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

Broader terms: arm bone

13

noun

Meaning 13

a circular region whose area is indicated by the length of its radius

Definition source: Princeton WordNet 3.0

Examples

  • they located it within a radius of 2 miles

Meaning relationships

Synonyms: none provided

Antonyms: none provided

Broader terms: region, part

14

noun

Meaning 14

a straight line from the center to the perimeter of a circle (or from the center to the surface of a sphere)

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

Broader terms: straight line

History

Etymology

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

Across languages

Translations

159 source translations are retained for this English entry.

  • Arabic: كُعْبُرَة (kuʕbura) — bone (human)
  • Arabic: كعبرة (kuʕbura) — bone (human)
  • Armenian: ճաճանչոսկր (čačančʻoskr) — bone (human)
  • Bulgarian: лъчева кост (lǎčeva kost) — bone (human)
  • Catalan: radi — bone (human)
  • Chinese Mandarin: 橈骨 /桡骨 (ráogǔ) — bone (human)
  • Czech: vřetenní kost — bone (human)
  • Dutch: spaakbeen — bone (human)
  • Dutch: radius — bone (human)
  • Esperanto: radiuso — bone (human)
  • Finnish: värttinäluu — bone (human)
  • French: radius — bone (human)
  • German: Speiche — bone (human)
  • German: Radius — bone (human)
  • Greek: κερκίδα (kerkída) — bone (human)
  • Hungarian: orsócsont — bone (human)
  • Ido: radiuso — bone (human)
  • Irish: gaghéag — bone (human)
  • Italian: radio — bone (human)
  • Japanese: 橈骨 (tōkotsu) — bone (human)
  • Kalmyk: шу (şu) — bone (human)
  • Kannada: ಮುಂಗೈ ಮೂಳೆ (muṅgai mūḷe) — bone (human)
  • Kazakh: кәрі жілік (kärı jılık) — bone (human)
  • Korean: 노뼈 (noppyeo) — bone (human)
  • Korean: 요골 (yogol) — bone (human)
  • Northern Kurdish: kewere — bone (human)
  • Malay: radius — bone (human)
  • Māori: āpiti — bone (human)
  • Mongolian: шуу (šuu) — bone (human)
  • Mongolian: шуу яс (šuu jas) — bone (human)
  • Old English: hresel — bone (human)
  • Persian: زند زبرین (zand-e zabarin) — bone (human)
  • Polish: kość promieniowa — bone (human)
  • Portuguese: rádio — bone (human)
  • Romanian: radius — bone (human)
  • Russian: лучева́я кость (lučevája kostʹ) — bone (human)
  • Serbo-Croatian: žbica — bone (human)
  • Serbo-Croatian: palčana kost — bone (human)
  • Spanish: radio — bone (human)
  • Telugu: రత్ని (ratni) — bone (human)
  • Ukrainian: променева кістка (promeneva kistka) — bone (human)
  • Vietnamese: xương quay — bone (human)
  • Volapük: radiut — bone (human)
  • Welsh: gwäell y fraich — bone (human)
  • Afrikaans: radius — line segment
  • Arabic: نِصْف قُطْر (niṣf quṭr) — line segment
  • Arabic: شُعَاع (šuʕāʕ) — line segment
  • Armenian: շառավիղ (šaṙaviġ) — line segment
  • Azerbaijani: radius — line segment
  • Basque: erradio — line segment
  • Belarusian: ра́дыус (rádyus) — line segment
  • Breton: skin — line segment
  • Bulgarian: ра́диус (rádius) — line segment
  • Burmese: အချင်းဝက် (a.hkyang:wak) — line segment
  • Catalan: radi — line segment
  • Cebuano: tungatid — line segment
  • Chinese Mandarin: 半徑 /半径 (bànjìng) — line segment
  • Czech: poloměr — line segment
  • Danish: radius — line segment
  • Dutch: straal — line segment
  • Esperanto: radiuso — line segment
  • Estonian: raadius — line segment
  • Faroese: radius — line segment
  • Finnish: säde — line segment
  • French: rayon — line segment
  • Friulian: rai — line segment
  • Galician: raio — line segment
  • Georgian: რადიუსი (radiusi) — line segment
  • German: Radius — line segment
  • German: Halbmesser — line segment
  • Greek: ακτίνα (aktína) — line segment
  • Gujarati: ત્રિજ્યા (trijyā) — line segment
  • Hebrew: רַדְיוּס (rádyus) — line segment
  • Hindi: त्रिज्या (trijyā) — line segment
  • Hungarian: sugár — line segment
  • Icelandic: radíus — line segment
  • Icelandic: geisli — line segment
  • Ido: radiuso — line segment
  • Indonesian: radius — line segment
  • Indonesian: jari-jari — line segment
  • Irish: ga — line segment
  • Italian: raggio — line segment
  • Japanese: 半径 (hankei) — line segment
  • Kannada: ತ್ರಿಜ್ಯ (trijya) — line segment
  • Kazakh: радиус (radius) — line segment
  • Korean: 반지름 (banjireum) — line segment
  • Korean: 반경 (ban'gyeong) — line segment
  • Northern Kurdish: nîvtîre — line segment
  • Latvian: rādiuss — line segment
  • Lithuanian: spindulys — line segment
  • Macedonian: радиус (radius) — line segment
  • Malay: jejari — line segment
  • Māori: pūtoro — line segment
  • Marathi: त्रिज्या (trijyā) — line segment
  • Mongolian: радиус (radius) — line segment
  • Norwegian Bokmål: radius — line segment
  • Norwegian Nynorsk: radius — line segment
  • Persian: شعاع (šo'â') — line segment
  • Polish: promień — line segment
  • Portuguese: raio — line segment
  • Punjabi: ਰੇਡੀਅਸ (reḍīasa) — line segment
  • Romanian: rază — line segment
  • Russian: ра́диус (rádius) — line segment
  • Scottish Gaelic: spòg — line segment
  • Serbo-Croatian: полупречник — line segment
  • Serbo-Croatian: poluprečnik — line segment
  • Slovak: polomer — line segment
  • Slovene: polmer — line segment
  • Spanish: radio — line segment
  • Swedish: radie — line segment
  • Tagalog: lihit — line segment
  • Telugu: వ్యాసార్థము (vyāsārthamu) — line segment
  • Thai: รัศมี (rát-sà-mǐi) — line segment
  • Turkish: yarıçap — line segment
  • Ukrainian: ра́діус (rádius) — line segment
  • Urdu: رداس (radās) — line segment
  • Urdu: نصف قطر (nisf-qutr) — line segment
  • Vietnamese: bán kính — line segment
  • Volapük: raid — line segment
  • Welsh: radiws — line segment
  • Yiddish: ראַדיוס (radyus) — line segment
  • Armenian: շառավիղ (šaṙaviġ) — length of this line segment
  • Belarusian: ра́дыус (rádyus) — length of this line segment
  • Bulgarian: ра́диус (rádius) — length of this line segment
  • Catalan: radi — length of this line segment
  • Chinese Mandarin: 半徑 /半径 (bànjìng) — length of this line segment
  • Czech: poloměr — length of this line segment
  • Dutch: straal — length of this line segment
  • Finnish: säde — length of this line segment
  • French: rayon — length of this line segment
  • German: Radius — length of this line segment
  • German: Halbmesser — length of this line segment
  • Hindi: त्रिज्या (trijyā) — length of this line segment
  • Hungarian: sugár — length of this line segment
  • Icelandic: radíus — length of this line segment
  • Icelandic: geisli — length of this line segment
  • Irish: ga — length of this line segment
  • Italian: raggio — length of this line segment
  • Japanese: 半径 (hankei) — length of this line segment
  • Korean: 반지름 (banjireum) — length of this line segment
  • Macedonian: радиус (radius) — length of this line segment
  • Macedonian: полупре́чник (polupréčnik) — length of this line segment
  • Malay: jejari — length of this line segment
  • Marathi: त्रिज्या (trijyā) — length of this line segment
  • Norwegian Bokmål: radius — length of this line segment
  • Norwegian Nynorsk: radius — length of this line segment
  • Polish: promień — length of this line segment
  • Portuguese: raio — length of this line segment
  • Romanian: rază — length of this line segment
  • Russian: ра́диус (rádius) — length of this line segment
  • Serbo-Croatian: полупречник — length of this line segment
  • Serbo-Croatian: poluprečnik — length of this line segment
  • Serbo-Croatian: polumjer — length of this line segment
  • Slovene: polmer — length of this line segment
  • Spanish: radio — length of this line segment
  • Swedish: radie — length of this line segment
  • Ukrainian: ра́діус (rádius) — length of this line segment
  • Volapük: raid — length of this line segment
  • Welsh: radiws — length of this line segment
Real reading context

radius in complete knowledge articles