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[nok-tuh-loo-suh nt] /ˌnɒk təˈlu sənt/
adjective, Meteorology
(of high-altitude clouds) visible during the short night of the summer.
Origin of noctilucent
1885-90; nocti- + lucent
Related forms
noctilucence, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for noctilucent
  • They are among the first such noctilucent clouds pictured this year.
  • After asking several astronomers, they are possible noctilucent clouds, airglow or faint aurora.
  • They are called noctilucent clouds, or night-shining clouds.
  • For years, scientists have puzzled over the observed increase in these noctilucent clouds.
  • These clouds are known as nacreous and noctilucent clouds respectively.
British Dictionary definitions for noctilucent


shining at night, usu. of very thin high altitude clouds observable in the summer twilight sky
Derived Forms
noctilucence, noun
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
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noctilucent in Science
Luminous at night. The term is used especially to describe certain high atmospheric cloud formations visible during summer nights at high latitudes.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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