radius

1. (anatomy) The long bone in the forearm, on the side of the thumb.Examples: "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.Synonyms: R

4. (geometry) A line segment between any point of a circle or sphere and its center.Examples: "Fatima claims to have visited all the bars within a five-mile radius of her Manhattan apartment."; "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."; "The velocity dispersions of early- and late-type galaxies in compact groups change little with groupcentric radius; the radii sampled are less than 100~h#123;-1#125; kpc, smaller than the radii typically sampled by members of massive clusters of galaxies."

5. (geometry) The length of this line segment.Examples: "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 ..."

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