noctilucent cloud

noun noc·ti·lu·cent cloud \ˌnäk-tə-ˈlü-sənt-\

Definition of noctilucent cloud

  1. :  a luminous thin usually colored cloud seen especially at twilight at a height of about 50 miles (80 kilometers)

Origin and Etymology of noctilucent cloud

noctilucent ultimately from Latin noct- + lucent-, lucens lucent

First Known Use: circa 1934

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