radiant

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ra·di·ant / ˈrādēənt/ • adj. 1. sending out light; shining or glowing brightly: a bird with radiant green and red plumage. ∎  (of a person or their expression) clearly emanating great joy, love, or health: she gave him a radiant smile. ∎  (of an emotion or quality) emanating powerfully from someone or something; very intense or conspicuous: he praised her radiant self-confidence. 2. (of heat) transmitted by radiation, rather than conduction or convection. ∎  (of an appliance) designed to emit such energy, esp. for cooking or heating. • n. a point or object from which light or heat radiates, esp. a heating element in an electric or gas heater. DERIVATIVES: ra·di·an·cy / -ənsē/ n. ra·di·ant·ly adv.

radiant The region of sky from which a meteor shower appears to emanate, as a result of perspective. In reality, meteoroids in a meteor stream pursue parallel orbits around the Sun, and enter the atmosphere along parallel trajectories. As an observational convenience, a radiant diameter of 8° is adopted. A meteor shower is named for the constellation in which its radiant lies (e.g. the Perseids emanate from Perseus). Because of the Earth's orbital motion, a radiant appears to drift eastwards by about 1° each day. Photographic and telescopic studies can reveal true radiant diameters and a degree of structure; splitting of a meteor stream by planetary perturbations, for instance, can result in showers with multiple sub-radiants.

radiant shining brightly XV; pert. to radiation XVIII. — L. radiāns, -ant-, prp. of radiāre radiate, f. radius RAY1.
Hence radiance XVII, radi-ancy XVII. So radiate (-ATE3) emit rays XVII; spread in all directions from a centre XIX. f. radiāt-, pp. stem of L. radiāre. radiation XVII. — L. radiator one or that which radiates XIX (in sense ‘apparatus for circulating hot water to warm an apartment’ orig. U.S.).

radiant see meteor shower .

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• deodorant •different, vociferant •belligerent, refrigerant •accelerant • tolerant • cormorant •itinerant • ignorant • cooperant •expectorant • adulterant •irreverent, reverent •nascent, passant •absent •accent, relaxant •acquiescent, adolescent, albescent, Besant, coalescent, confessant, convalescent, crescent, depressant, effervescent, erubescent, evanescent, excrescent, flavescent, fluorescent, immunosuppressant, incandescent, incessant, iridescent, juvenescent, lactescent, liquescent, luminescent, nigrescent, obsolescent, opalescent, pearlescent, phosphorescent, pubescent, putrescent, quiescent, suppressant, tumescent, turgescent, virescent, viridescent •adjacent, complacent, obeisant •decent, recent •impuissant, reminiscent •Vincent • puissant •beneficent, maleficent •magnificent, munificent •Millicent • concupiscent • reticent •docent •lucent, translucent •discussant, mustn't •innocent •conversant, versant •consentient, sentient, trenchant •impatient, patient •ancient • 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