noctilucent.

1. Visible or glowing at night, especially when a high cloud remains illuminated after sunset.

2. Producing visible light through a biological process, as certain organisms do.

Use it for

Words that belong together

• noctilucent clouds
• noctilucent display

On the page

Noctilucent clouds hung like pale blue threads above the darkened hills.

Usage notes

Primary category: poetic / figurative / atmospheric. Lexical Type: Word. Forms: Normally non-gradable; no ordinary comparative or superlative. Commonness: uncommon (editorial estimate; not a corpus frequency statistic). Legacy lexical fields mirror sense 1; numbered fields keep each relevant meaning separate. Research distinction: MW distinguishes general night visibility from biological light production. Noctilucent clouds may remain sunlit and must not be mislabeled bioluminescent. Writing functions: atmospheric description, sensory precision.