noun (plural radii /ˈrādēˌī/ or radiuses)
1A straight line from the center to the circumference of a circle or sphere. See also illustration at geometric.
- Thus, the area of a circle is equal to half of the product of the radius and the circumference.
- He calculates the side of a regular pentagon in terms of the radius of the circumscribed circle.
- Recall that given a circle of radius r, the circumference is 2pr.
1.1A radial line from the focus to any point of a curve.
- These apply to clear zones on the outside of horizontal curves with a radius of 900 m or less.
- Key factors to meet the new criteria include the length and width of runways, the width and curve radii of taxiways, and also the airport's pavement loading limits.
- Second, this lightweight insert extends the bullet nose and accommodates use of a longer ogive - the radius of the curve of the bullet tip.
1.2The length of the radius of a circle or sphere.
- The cone shaped tip is just under one micrometer in length and has a radius of a few nanometers at its apex.
- Interestingly, though the analysis points to a ball with an average radius of 1.584 inches, the measured radius of a real baseball is 1.452 inches.
- Stephenson, who constructed both projects, believed that gradients should be less than 1 percent and that curves should have very wide radii of at least a kilometre.
1.3A specified distance from a center in all directions: there are plenty of local pubs within a two-mile radius
More example sentences
- It seems sensible to find somewhere with no population centres within a two-mile radius - like offshore.
- The department has acquired legal powers to close all footpaths within a two-mile radius of any free-range poultry farms.
- Teams divided into four groups, combing through a two-mile radius searching for any clue of what might have happened.
2 Anatomy The thicker and shorter of the two bones in the human forearm. Compare with ulna.
- Common osteoporotic fracture sites include the vertebrae, the hip, the distal radius of the forearm, and the proximal humerus.
- Scaphoid fractures are rare children and the elderly because of the relative weakness of the distal radius compared with the scaphoid in these age groups.
- Abduction is movement of the hand away from the body as the proximal carpal bones move medially on the radius.
2.1 Zoology The corresponding bone in a vertebrate’s foreleg or a bird’s wing.
- For example, the radius, one of the lower bones of the foreleg, became much broader.
- As is usual in chelonioids, the radius is notably longer than the ulna.
- In the equid foreleg, radius and ulna are united, and the ulna is greatly reduced so that all weight is born on the radius.
Late 16th century (sense 2): from Latin, literally 'staff, spoke, ray'.
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