Learn how to say Noctilucent correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word noctilucent cloud:
a luminous cloud of a kind occasionally seen at night in summer in high latitudes, at the altitude of the mesopause:
he estimated the height of the noctilucent clouds he saw at 80 to 100 km
late 19th century: from Latin nox, noct- ‘night’ + lucere ‘to shine’ + -ent