umbral

Variant of umbra

noun pl. umbrae or umbras

  1. shade or a shadow
  2. the dark central cone of shadow projecting from a planet or satellite on the side opposite the sun
  3. the dark central part of a sunspot
  4. Rare a phantom, or ghost
  5. Physics a perfect or complete shadow, in which no direct light is received from the source of illumination

Origin: L, a shade, shadow

Related Forms:

Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.
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