1. (n.) A right line drawn or extending from the center of a circle to the periphery; the semidiameter of a circle or sphere.

2. (n.) The preaxial bone of the forearm, or brachium, corresponding to the tibia of the hind limb

3. (n.) A ray, or outer floret, of the capitulum of such plants as the sunflower and the daisy. See Ray.

4. (n.) The barbs of a perfect feather.

5. (n.) Radiating organs, or color-markings, of the radiates.

6. (n.) The movable limb of a sextant or other angular instrument.

O air line ambit amplitude annular muscle annulus approach area areola asymptote aureole axis beeline bigness body bore bottleneck breadth bulk caliber carry chaplet chord circle circuit circumference circus closed circle collision course compass concentralization concentration concourse concurrence confluence conflux congress convergence converging corona coronet coverage crossing crown cycle depth diadem diagonal diameter diapason diffusion dimension dimensions direct line directrix discus disk dispersion edge emanation eternal return expanse expansion extension extent fairy ring focalization focus funnel gamut garland gauge girth glory great-circle course greatness halo height hub largeness lasso length logical circle loop looplet magic circle magnitude mass measure measurement meeting mutual approach narrowing gap noose normal orbit perpendicular proportion proportions purview radiance radiation radius vector range ray reach register right line ring rondelle round roundel saucer scale scattering scope secant segment semidiameter shortcut side size spectrum sphincter spoke spokes spread straight straight course straight line straight stretch straightaway streamline stretch sweep tangent transversal vector vicious circle volume wheel width wreath