radiant

Etymology

From Middle French radiant, from Latin radians, radiantis, present participle of radiare (“to emit rays or beams”).

adj

1. Radiating light and/or heat.
   the radiant sun
2. Emitted as radiation.
3. Beaming with vivacity and happiness.
   a radiant face
4. Strikingly beautiful.
   And yet she was ensnaringly beautiful, despite her pride and self-consciousness; radiant and certain of conquest she stood before the man who alone seemed to have neither eye nor ear for charms that had never elsewhere played her false. 1893, E. Werner, Clear the Track!, page 94
5. Emitting or proceeding as if from a center.
6. (heraldry) Giving off rays; said of a bearing.
   the sun radiant;  a crown radiant
7. (botany) Having a ray-like appearance, like the large marginal flowers of certain umbelliferous plants; said also of the cluster which has such marginal flowers.

noun

1. A point source from which radiation is emitted.
2. (astronomy) The apparent origin, in the night sky, of a meteor shower.
3. (geometry) A straight line proceeding from a given point, or fixed pole, about which it is conceived to revolve.