| radian | <mathematics> An arc of a circle which is equal to the radius, or the angle measured by such an arc. Origin: From Radius. Source: Websters Dictionary (01 Mar 1998) |
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| radiant | 1. Emitting or proceeding as from a center; rays; radiating; radiate. 2. Especially, emitting or darting rays of light or heat; issuing in beams or rays; beaming with brightness; emitting a vivid light or splendor; as, the radiant sun. "Mark what radiant state she spreads." (Milton) 3. Beaming with vivacity and happiness; as, a radiant face. 4. Giving off rays; said of a bearing; as, the sun radiant; a crown radiant. 5. <botany> Having a raylike appearance, as the large marginal flowers of certain umbelliferous plants; said also of the cluster which has such marginal flowers. <physics> Radiant energy See Radiant. Origin: L. Radians, -antis, p. Pr. Of radiare to emit rays or beams, fr. Radius ray: cf. F. Radiant. See Radius, Ray a divergent line. 1. <optics> The luminous point or object from which light emanates; also, a body radiating light brightly. 2. <geometry> A straight line proceeding from a given point, or fixed pole, about which it is conceived to revolve. 3. <astronomy> The point in the heavens at which the apparent paths of shooting stars meet, when traced backward, or whence they appear to radiate. Source: Websters Dictionary (01 Mar 1998) |
| radiant energy | Energy contained in light rays or any other form of radiation. (05 Mar 2000) |
| radiant heat | Heat given off from any body in the form of waves, similar to light waves but of greater wavelength. (05 Mar 2000) |
| radiant intensity | The luminous flux per unit solid angle in a given direction. Synonym: candle-power, radiant intensity. (05 Mar 2000) |