ray¹ / rā/ • n. 1. each of the lines in which light (and heat) may seem to stream from the sun or any luminous body, or pass through a small opening: a ray of sunlight came through the window. ∎  the straight line in which light or other electromagnetic radiation travels to a given point. ∎  (rays) a specified form of nonluminous radiation: water reflects and intensifies UV rays. ∎  Math. any of a set of straight lines passing through one point. ∎  (rays) inf., sunlight considered in the context of sunbathing: catch some rays on a secluded sandy beach. ∎ fig. an initial or slight indication of a positive or welcome quality in a time of difficulty or trouble: if only I could see some ray of hope. 2. a thing that is arranged radially, in particular: ∎  Bot. (in a composite flowerhead of the daisy family) an array of ray florets arranged radially around the central disc, forming the white part of the flowerhead of a daisy. ∎  (also fin ray) Zool. each of the long, slender bony protuberances supporting the fins of most bony fishes. ∎  Zool. each radial arm of a starfish.• v. [intr.] spread from or as if from a central point: delicate lines rayed out at each corner of her eyes. ∎  [tr.] poetic/lit. radiate (light): the sun rays forth its natural light into the air.PHRASES: ray of sunshine inf. a person or thing that brings happiness into the lives of others.DERIVATIVES: ray·less adj. ( chiefly Bot. ).ray² • n. a broad, flat marine or freshwater fish (Rajidae and other families) with a cartilaginous skeleton, winglike pectoral fins, and a long slender tail. Many rays have venomous spines or electric organs.