nacreous cloud is a noun meaning "a luminous iridescent cloud at a high altitude that may be seen when the sun is a few degrees below the horizon". It carries one recorded sense.
a luminous iridescent cloud at a high altitude that may be seen when the sun is a few degrees below the horizon
Definitions, synonyms and semantic relations for nacreous cloud come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.