['re?d??s]
¦ noun (plural radii -d??? or radiuses)
1. a straight line from the centre to the circumference of a circle or sphere.
a radial line from the focus to any point of a curve.
2. a specified distance from a centre in all directions: there are plenty of pubs within a two-mile radius.
3. Anatomy & Zoology a bone of the forearm or forelimb, in humans the thicker and shorter of two.
4. Zoology a radially symmetric feature in an echinoderm or coelenterate, e.g. an arm of a starfish.
5. Entomology a main vein in an insect's wing.
¦ verb (radiuses, radiusing, radiused) [often as adjective radiused] make (a corner or edge) rounded.
Origin
C16: from L., lit. 'staff, spoke, ray'.