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.

(01 Mar 1998)