∙ Having a ray-like appearance, like the large marginal flowers of certain umbelliferous plants; said also of the cluster which has such marginal flowers. botany
Noun
∙ A point source from which radiation is emitted.
∙ The apparent origin, in the night sky, of a meteor shower. astronomy
∙ A straight line proceeding from a given point, or fixed pole, about which it is conceived to revolve.