ra·di·us

(rā′dē-əs)

n. pl. ra·di·i (-dē-ī′) or ra·di·us·es

1. Abbr. r or rad. Mathematics

a. A line segment that joins the center of a circle with any point on its circumference.

b. A line segment that joins the center of a sphere with any point on its surface.

c. A line segment that joins the center of a regular polygon with any of its vertices.

d. The length of any such line segment.

2. A circular area measured by a given radius: every family within a radius of 25 miles of the city center.

3. A bounded range of effective activity or influence: the operating radius of a helicopter.

4. A radial part or structure, such as a mechanically pivoted arm or the spoke of a wheel.

5. Anatomy

a. A long, prismatic, slightly curved bone in humans, the shorter and thicker of the two forearm bones, located on the lateral side of the ulna.

b. A similar bone in many other vertebrates.

[Latin, ray, spoke of a wheel, radius; see ray¹.]

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

radius

(ˈreɪdɪəs)

n, pl -dii (-dɪˌaɪ) or -diuses

1. (Mathematics) a straight line joining the centre of a circle or sphere to any point on the circumference or surface

2. (Mathematics) the length of this line, usually denoted by the symbol r

3. (Mathematics) the distance from the centre of a regular polygon to a vertex (long radius) or the perpendicular distance to a side (short radius)

4. (Anatomy) anatomy the outer and slightly shorter of the two bones of the human forearm, extending from the elbow to the wrist

5. (Zoology) a corresponding bone in other vertebrates

6. (Zoology) any of the veins of an insect's wing

7. (Botany) a group of ray florets, occurring in such plants as the daisy

a. any radial or radiating part, such as a spoke

b. (as modifier): a radius arm.

9. (Mechanical Engineering) the lateral displacement of a cam or eccentric wheel

10. a circular area of a size indicated by the length of its radius: the police stopped every lorry within a radius of four miles.

11. the operational limit of a ship, aircraft, etc

[C16: from Latin: rod, ray, spoke]

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

ra•di•us

(ˈreɪ di əs)

n., pl. -di•i (-diˌaɪ)
-di•us•es.

1. a straight line extending from the center of a circle or sphere to the circumference or surface: The radius of a circle is half the diameter.

2. the length of such a line.

3. any radial or radiating part.

4. a circular area having an extent determined by the length of the radius from a given or specified central point: every house within a radius of 50 miles.

5. a field or range of operation or influence.

6. extent of possible operation, travel, etc., as under a single supply of fuel.

7. the bone of the forearm on the thumb side.

8. a corresponding bone in the forelimb of other vertebrates.

[1590–1600; < Latin: staff, rod, spoke, beam, ray¹]

ra·di·us

(rā′dē-əs)

Plural radii (rā′dē-ī′) or radiuses

1. A line segment that joins the center of a circle or sphere with any point on the circumference of the circle or the surface of the sphere. It is half the length of the diameter.

2. The shorter and thicker of the two bones of the forearm or the lower portion of the foreleg. See more at skeleton.

The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

radius

One of the two bones of the forearm.

ThesaurusAntonymsRelated WordsSynonymsLegend:

Noun	1.	radius - the length of a line segment between the center and circumference of a circle or sphere r diam, diameter - the length of a straight line passing through the center of a circle and connecting two points on the circumference semidiameter - the apparent radius of a celestial body when viewed as a disc from the earth radius of curvature - the radius of the circle of curvature; the absolute value of the reciprocal of the curvature of a curve at a given point length - the linear extent in space from one end to the other; the longest dimension of something that is fixed in place; "the length of the table was 5 feet"
	2.	radius - a straight line from the center to the perimeter of a circle (or from the center to the surface of a sphere) straight line - a line traced by a point traveling in a constant direction; a line of zero curvature; "the shortest distance between two points is a straight line"
	3.	radius - a circular region whose area is indicated by the length of its radius; "they located it within a radius of 2 miles" region, part - the extended spatial location of something; "the farming regions of France"; "religions in all parts of the world"; "regions of outer space"
	4.	radius - the outer and slightly shorter of the two bones of the human forearm forearm - the part of the superior limb between the elbow and the wrist arm bone - a bone in the arm
	5.	radius - support consisting of a radial member of a wheel joining the hub to the rim spoke, wheel spoke bicycle wheel - the wheel of a bicycle cartwheel - a wheel that has wooden spokes and a metal rim support - any device that bears the weight of another thing; "there was no place to attach supports for a shelf" wagon wheel - a wheel of a wagon

Translations

نِصْف القُطر

poloměrokruh

afstandradius

Radius Speiche Umkreis

ακτίνα

radio

sädevärttinäluu

rayon radius

hatósugár

radíusgeisli

polomer

polmer

yarı çapyarı çap çizgisi

半径范围

radius

[ˈreɪdɪəs] N (radiuses, radii (pl)) → radio m
within a radius of 50 miles → en un radio de 50 millas

Collins Spanish Dictionary - Complete and Unabridged 8th Edition 2005 © William Collins Sons & Co. Ltd. 1971, 1988 © HarperCollins Publishers 1992, 1993, 1996, 1997, 2000, 2003, 2005

radius

[ˈreɪdiəs] [radii] (pl) n

(gen) → rayon m
within a radius of 50 km → dans un rayon de 50 km

(MATHEMATICS) → rayon m

(ANATOMY) → radius m

Collins English/French Electronic Resource. © HarperCollins Publishers 2005

radius

n pl <radii>

(Math) → Radius m, → Halbmesser m; (of ship, aircraft) → Aktionsradius m, → Wirkungsbereich m; within a 6 km radius (of Hamburg) → in einem Umkreis von 6 km (von Hamburg)

(Anat) → Speiche f

Collins German Dictionary – Complete and Unabridged 7th Edition 2005. © William Collins Sons & Co. Ltd. 1980 © HarperCollins Publishers 1991, 1997, 1999, 2004, 2005, 2007

radius

[ˈreɪdɪəs] n (radii (pl)) [ˈreɪdɪaɪ] (Math) (fig) → raggio (Anat) → radio
within a radius of 50 miles → in un raggio di 50 miglia

radius

(ˈreidiəs) noun

1. (plural ˈradiuses) the area within a given distance from a central point. They searched within a radius of one mile from the school.

2. (plural ˈradii (-diai) ) a straight line from the centre of a circle to its circumference.

ra·di·us

n. radio.

1. hueso largo del antebrazo;

2. línea recta que une el centro y cualquier punto de la circunferencia.

radius

n (pl radii) radio

Mentioned in

References in classic literature

-- After what has been said above, it will be necessary, first of all, to choose the period when the moon will be in perigee, and also the moment when she will be crossing the zenith, which latter event will further diminish the entire distance by a length equal to the radius of the earth, i.

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If on Friday night you had taken a pair of compasses and drawn a circle with a radius of five miles round the Woking sand pits, I doubt if you would have had one human being outside it, unless it were some relation of Stent or of the three or four cyclists or London people lying dead on the common, whose emotions or habits were at all affected by the new-comers.

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We can't charge more than sixpence a mile after the first, within the four-mile radius. This very morning I had to go a clear six miles and only took three shillings.

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It was not quite so far off as could have been wished; but it was probably far enough, her radius of movement and repute having been so small.

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He who wears one of its mates will experience the same feeling; it is caused by an electrical action that takes place the moment two of these gems cut from the same mother stone come within the radius of each other's power.

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If a number of equal spheres be described with their centres placed in two parallel layers; with the centre of each sphere at the distance of radius x sqrt(2) or radius x 1.41421 (or at some lesser distance), from the centres of the six surrounding spheres in the same layer; and at the same distance from the centres of the adjoining spheres in the other and parallel layer; then, if planes of intersection between the several spheres in both layers be formed, there will result a double layer of hexagonal prisms united together by pyramidal bases formed of three rhombs; and the rhombs and the sides of the hexagonal prisms will have every angle identically the same with the best measurements which have been made of the cells of the hive-bee.

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The theoretic effective radius of this rifle is three hundred miles, but the best they can do in actual service when equipped with their wireless finders and sighters is but a trifle over two hundred miles.

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As there was not a single town or large village in the vicinity of the camp, the immense number of generals and courtiers accompanying the army were living in the best houses of the villages on both sides of the river, over a radius of six miles.

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Now they were moving rapidly in pursuit of us, all well within the radius of a mile.

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During these days the boy rode Sir Mortimer abroad in many directions until he knew every bypath within a radius of fifty miles of Torn.

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"Yes, my worthy friend; taking into consideration all the elements of the problem, the distance from the center of the earth to the center of the moon, of the radius of the earth, of its bulk, and of the bulk of the moon, I can tell exactly what ought to be the initiatory speed of the projectile, and that by a simple formula."

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Bwana never countenanced such acts in his country and his word was law among those who hunted within a radius of many miles of his estate.

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