emitting rays of light; shining; bright: the radiant sun; radiant colors.
bright with joy, hope, etc.: radiant smiles; a radiant future.
Physics. emitted or propagated by radiation.
  1. noting a partition line having a series of flamelike indentations formed by ogees joined in zigzags; rayonny.
  2. (of a charge, as an ordinary) having an edge or edges so formed.


Origin of radiant

1400–50; late Middle English < Latin radiant- (stem of radiāns, present participle of radiāre to radiate light, shine), equivalent to radi(us) beam, ray (see radius) + -ant- -ant
Related formsra·di·ant·ly, adverban·ti·ra·di·ant, adjectivenon·ra·di·ant, adjectivenon·ra·di·ant·ly, adverbsu·per·ra·di·ant, adjectiveun·ra·di·ant, adjective

Synonyms for radiant

Synonym study

1. See bright.

Antonyms for radiant

1. dim.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for radiant

Contemporary Examples of radiant

Historical Examples of radiant

  • He looked upward with a radiant expression, and feebly pressed her hand.


    Lydia Maria Child

  • Gilder sprang to his feet, his face suddenly grown younger, radiant.

    Within the Law

    Marvin Dana

  • She was obliged to go, and to appear all radiant with pleasure.

  • To the widow of Mr Verloc the robust anarchist was like a radiant messenger of life.

    The Secret Agent

    Joseph Conrad

  • There is a radiant picture of this morning ride still fresh in my memory.

    In the Valley

    Harold Frederic

British Dictionary definitions for radiant



sending out rays of light; bright; shining
characterized by health, intense joy, happiness, etca radiant countenance
emitted or propagated by or as radiation; radiatedradiant heat
sending out heat by radiationa radiant heater
physics (of a physical quantity in photometry) evaluated by absolute energy measurementsradiant flux; radiant efficiency Compare luminous


a point or object that emits radiation, esp the part of a heater that gives out heat
astronomy the point in space from which a meteor shower appears to emanate
Derived Formsradiantly, adverb

Word Origin for radiant

C15: from Latin radiāre to shine, from radius ray of light, radius
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for radiant

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.


"point or object from which light radiates," 1727; see radiant (adj.). In astronomy, of meteor showers, from 1864.

Online Etymology Dictionary, © 2010 Douglas Harper

radiant in Medicine




Emitting heat or light.
Consisting of or emitted as radiation.


A point from which light radiates to the eye.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

radiant in Science




Transmitting light, heat, or other radiation. Stars, for example, are radiant bodies.
Consisting of or transmitted as radiation.


The apparent celestial origin of a meteor shower. For example, a point in the constellation Gemini is the radiant of the Geminid meteor shower.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.