noctilucent UK /ˌnɒktɪˈluːsənt/US /ˌnɑktəˈlusənt/ adjective1 •Shining or glowing at night, especially of very high-altitude clouds that reflect sunlight long after sunset; nightshining.[…] fireflies and other noctilucent insects. — 1891 formsmore noctilucent · most noctilucent
