From Longman Dictionary of Contemporary Englishcloudbankcloud‧bank /ˈklaʊdbæŋk/ noun [countable] British English HEMa thick mass of low cloud
Examples from the Corpus
cloudbank• A low, scudding cloudbank was coming off the western horizon, purple with unshed rain.• The cloudbank spread, seeming to soak up the light.• Lightning struck out of the towering cloudbank. 