Main Entry: noc·ti·lu·cent cloud

Pronunciation: \ˌnäk-tə-ˈlü-s^ənt-\

Function: noun

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

Date: 1910

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