a rarely seen, luminous, iridescent cloud shaped like a cirrus or altocumulus, approximately 15 mi. (24 km) above the earth, and of unknown composition. Also called mother-of-pearl cloud .
NACREOUS CLOUD
Meaning of NACREOUS CLOUD in English
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012