Radiant heat

Radiant \Ra"di*ant\ (r[=a]"d[i^]*ant), a. [L. radians, -antis,
   p. pr. of radiare to emit rays or beams, fr. radius ray: cf.
   F. radiant. See {Radius}, {Ray} a divergent line.]
   1. Emitting or proceeding as from a center; resembling rays;
      radiating; radiate.
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   2. Especially, emitting or darting rays of light or heat;
      issuing in beams or rays; beaming with brightness;
      emitting a vivid light or splendor; as, the radiant sun.
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            Mark what radiant state she spreads.  --Milton.
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   3. Beaming with vivacity and happiness; as, a radiant face.
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   4. (Her.) Giving off rays; -- said of a bearing; as, the sun
      radiant; a crown radiant.
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   5. (Bot.) Having a raylike appearance, as the large marginal
      flowers of certain umbelliferous plants; -- said also of
      the cluster which has such marginal flowers.
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   6. (Physics) Emitted or transmitted by radiation; as, a
      radiant energy; radiant heat.
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   {Radiant energy} (Physics), energy given out or transmitted
      by radiation, as in the case of light and radiant heat.

   {Radiant heat}, heat proceeding in right lines, or directly
      from the heated body, after the manner of light, in
      distinction from heat conducted or carried by intervening
      media.

   {Radiant point}. (Astron.) See {Radiant}, n., 3.
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