CS Knowledge Base

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

• enPR: rā'-dē-əs, IPA^(key): /ˈɹeɪ.di.əs/

• Audio (US):

  (file)

• Rhymes: -eɪdiəs
• Hyphenation: ra‧di‧us

radius (plural radii or radiuses)

1. (anatomy) The long bone in the forearm, on the side of the thumb.
   • 1808, John Barclay, The Muscular Motions of the Human Body‎^[1], →OCLC, page 396:

     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. (zoology) The lighter bone (or fused portion of bone) in the forelimb of an animal.
3. (entomology) 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.
5. (geometry) 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.

   • 1994, Viacheslav V. Nikulin, Igor R. Shafarevich, translated by Miles Reid, Geometries and Groups, Springer, page 194:

     We start with spherical geometries. The two geometries on spheres of radiuses R₁ and R₂ are obviously identical if R₁ = R₂; moreover, the converse also holds.

   • 2016, Jubee Sohn, Ho Seong Hwang, Margaret J. Geller, Antonaldo Diaferio, Kenneth J. Rines, Myung Gyoon Lee, Gwang-Ho Lee, “Compact Groups of Galaxies with Complete Spectroscopic Redshifts in the Local Universe”, in JKAS‎^[2], volume 2015:

     The velocity dispersions of early- and late-type galaxies in compact groups change little with groupcentric radius; the radii sampled are less than kpc, smaller than the radii typically sampled by members of massive clusters of galaxies.

6. (geometry) The length of this line segment.
   • 1998, Dieter Schuocker, Handbook of the Eurolaser Academy, Springer Science & Business Media, →ISBN, page 51:

     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 ...

7. 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.
   • 1674, Robert Hooke, Animadversions on the Firſt Part of the Machina Coelestis of the […] Aſtronomer Johannes Hevelius […] ‎^[3], page 43:

     […] 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; […]

8. (graph theory) The minimum eccentricity of any vertex, for a given graph.

• (vein of insect wing): R

• radial
• radiad
• radiate, radiation

radius (third-person singular simple present radiuses, present participle radiusing, simple past and past participle radiused)

1. (transitive) To give a rounded edge to.
   • 2014, Anil Mital, Anoop Desai, Anand Subramanian, Product Development, page 358:

     A comfortable grip is ensured by smoothing the surface of the handle and radiusing the edge.

• ulna
• semidiameter
• Radius on Wikipedia.Wikipedia
• Radius (bone) on Wikipedia.Wikipedia

• Darius

Other scripts
Cyrillic	радиус
Roman

Borrowed from Russian радиус (radius), from Latin radius.

radius

1. radius (line segment or length of this line segment)

• Mirjejev, V. A.; Usejinov, S. M. (2002), Ukrajinsʹko-krymsʹkotatarsʹkyj slovnyk [Ukrainian – Crimean Tatar Dictionary]‎^[4], Simferopol: Dolya, →ISBN
• “radius”, in Luğatçıq (in Russian)

Borrowed from Latin radius.

radius c (singular definite radien or radiusen, plural indefinite radier or radiuser)

1. (geometry) radius

• “radius” in Den Danske Ordbog

• IPA^(key): /raˈdius/

• Audio:

  (file)

• Rhymes: -ius
• Syllabification: ra‧di‧us

radius

1. conditional of radii

radius m (genitive singular radius, plural radiusar)

1. (geometry) radius

Borrowed from Latin radius. Doublet of rai, which was inherited.

• IPA^(key): /ʁa.djys/

• Audio:

  (file)

• Audio (France (Vosges)):

  (file)

radius m (invariable)

1. (anatomy) radius

• “radius”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012

• durais

radius

1. conditional of radiar

Learned borrowing from Latin radius.

• IPA^(key): /raˈdiʊs/
• Hyphenation: ra‧di‧us

radius (plural radius-radius)

1. radius:
   1. (mathematics) a line segment between any point of a circle or sphere and its center; the length of this line segment

      Synonyms: jari-jari, ruji-ruji

   2. (anatomy) the long bone in the forearm, on the side of the thumb

      Synonym: pengumpil

2. area of a circle, commonly with epicenter as center

• “radius”, in Kamus Besar Bahasa Indonesia [Great Dictionary of the Indonesian Language] (in Indonesian), Jakarta: Agency for Language Development and Cultivation – Ministry of Education, Culture, Research, and Technology of the Republic of Indonesia, 2016

Of uncertain origin.^[1] Some connect it with rādīx and rāmus. Tucker suggests Proto-Indo-European *neredʰ- (“extend forth, rise, outward”) akin to Sanskrit वर्धते (vardhate, “rise, grow”), or from Ancient Greek ἄρδις (árdis, “sharp point”).^[2] May ultimately be from Proto-Indo-European *reh₁t- (“bar, beam, stem”).

• (Classical Latin) IPA^(key): [ˈra.di.ʊs]
• (modern Italianate Ecclesiastical) IPA^(key): [ˈraː.di.us]

radius m (genitive radiī or radī); second declension

1. a staff, rod
   1. a spoke of a wheel
   2. a rod for measurement
   3. the radius of a circle; a rotating radial arm
   4. (weaving) a shuttle
   5. (poetic) a bolt or shaft
   6. the spur of a bird's leg
   7. the tail-spine of a stingray
   8. (anatomy) the radius (the outer bone of a forearm)
2. a ray of light (also reflected)
   • 29 BCE – 19 BCE, Vergilius, Aeneid 4.118-119:

     “[...] ubi prīmōs crāstinus ortus
     extulerit Tītān, radiīsque retēxerit orbem.”

     “[...] when at tomorrow’s early dawn the Titan [Sun] will have risen, and with [his] rays revealed the world.”

   • 8 CE, Ovidius, Fasti 6.717:

     At pater Hēliadum radiōs ubi tīnxerit undīs

     But when the father of the Heliades shall have dipped his rays in the waves [...].
     (The father is the sun god; see: Heliades.)

   1. (according to an ancient theory of vision) a ray extending from the eye to the object seen
3. the name of an elongated variety of olive
4. the name of a rod with which geometers make figures in dust, also known as a virga

Second-declension noun.

¹Found in older Latin (until the Augustan Age).

• radiō
• radiolus

Learned borrowings

• “radius” on page 1731 of the Oxford Latin Dictionary (2nd ed., 2012)
• “radius”, in Charlton T. Lewis and Charles Short (1879), A Latin Dictionary, Oxford: Clarendon Press
• “radius”, in Charlton T. Lewis (1891), An Elementary Latin Dictionary, New York: Harper & Brothers
• "radius", in Charles du Fresne du Cange, Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• “radius”, in Gaffiot, Félix (1934), Dictionnaire illustré latin-français, Hachette.
• “radius”, in Harry Thurston Peck, editor (1898), Harper’s Dictionary of Classical Antiquities, New York: Harper & Brothers
• “radius”, in William Smith et al., editor (1890), A Dictionary of Greek and Roman Antiquities, London: William Wayte. G. E. Marindin

Borrowed from Latin radius.

radius m (definite singular radien or radiusen, indefinite plural radier, definite plural radiene)

1. (geometry) radius

• “radius” in The Bokmål Dictionary.

Borrowed from Latin radius.

radius m (definite singular radiusen, indefinite plural radiusar, definite plural radiusane)

1. (geometry) radius

• “radius” in The Nynorsk Dictionary.

Borrowed from French radius, Latin radius. Compare the inherited doublet rază (“ray”).

radius n (plural radiusuri)

1. (anatomy) radius (bone)

• radiu