Radius

rā′di-us, n. ( geom. ) a straight line from the centre to the circumference of a circle: anything like a radius, as the spoke of a wheel: a ray: ( an at. ) the exterior bone of the arm: ( bot. ) the ray of a flower: the movable arm of a sextant: one of the radiating lines of a geometrical spider's web:— pl. Rā′dii (ī).— ns. Rā′dius-bar , -rod , in a steam-engine, a rod pivoted at one end and connected at the other with a concentrically moving part at a fixed distance.— Radius vector ( pl. Radii vectores ), the distance from a fixed origin to any point of a curve. [L., a rod.]