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.


Nearby words

  1. radial-ply,
  2. radially,
  3. radian,
  4. radiance,
  5. radiancy,
  6. radiant ,
  7. radiant efficiency,
  8. radiant emittance,
  9. radiant energy,
  10. radiant exitance

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 forms

Synonym study

1. See bright.

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

Examples from the Web for radiant

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
Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for radiant




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.

Science definitions for radiant




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.