radius

American  

[rey-dee-uhs] / ˈreɪ di əs /

noun

plural

radii, radiuses

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.

   the flying radius of an airplane.

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

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

9. Machinery Now Rare. the throw of an eccentric wheel or cam.

10. a rounded corner or edge on a machined or cast piece of metal.

11. Entomology. one of the principal longitudinal veins in the anterior portion of the wing of an insect.

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radius British  

/ ˈreɪdɪəs /

noun

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

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

3. 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 the outer and slightly shorter of the two bones of the human forearm, extending from the elbow to the wrist

5. a corresponding bone in other vertebrates

6. any of the veins of an insect's wing

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

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

   2. ( as modifier )

      a radius arm

9. 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

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radius Scientific  

/ rā′dē-əs /

plural

radii

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.

3. See more at skeleton

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Etymology

Origin of radius

First recorded in 1590–1600; from Latin: “staff, rod, spoke, beam,” originally, “ray”; ray ¹

Example Sentences

But if the AI trade were to blow up, he said, the blast radius could be wide.

From The Wall Street Journal

But one tour group’s dream is a tour group leader’s safety concern, so they traced the edge of the blimp’s swing radius, staying out of reach of the resting giant.

From Los Angeles Times

“I recognize a lot of similarities between him and me. So we grew up literally in the same radius, in the same neighborhood together,” Hicks told a local Chicago news station in May.

From The Wall Street Journal

At intermediate intensity, the expansion stage is followed by a reduction in the radius observed in X-ray images.

From Science Daily

“It was likely meant to be confidential, but anyone within a mile’s radius could hear them.”

From The Wall Street Journal