mid-15c., from Middle French radiant and directly from Latin radiantem (nominative radians) "beaming, shining," present participle of radiare "to beam, shine" (see radiation). Of beauty, etc., first attested c. 1500. Related: Radiantly.
radiant (n.)
"point or object from which light radiates," 1727; see radiant (adj.). In astronomy, of meteor showers, from 1864.
a radiant sunrise
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