From Longman Dictionary of Contemporary Englishcumuluscu‧mu‧lus /ˈkjuːmjələs/ noun [countable, uncountable] DNa thick white cloud with a flat bottom edge
Examples from the Corpus
cumulus• These clouds are unbroken, and never, for example, look like the billowy cumulus clouds of the Earth.• He stood against them, watching the dark western sky and the ash-blue cumulus now edged with brilliant white.• The sky is piled with sunlit June cumulus.• The sky was blue, muddied with vast banks of cloud like cumulus from a volcano.• The first hour proved fairly turbulent, as we skimmed under some cumulus build-ups.• The cumulus cells will disperse gradually to release the enclosed eggs over the next 2-4 min.• In fact the mountains were cumulus clouds and the roaring sound came from the surf.• Shasta because of the chance of thunderstorms, with cumulus building on the 14,162-foot summit early in the morning.Origin cumulus (1800-1900) Modern Latin Latin, “pile, mass” 