cu·mu·lo·nim·bus  (kyōōm'yə-lō-nĭm'bəs)  n. pl. cu·mu·lo·nim·bus·es or cu·mu·lo·nim·bi (-bī) An extremely dense, vertically developed cumulus with a relatively hazy outline and a glaciated top extending to great heights, usually producing heavy rains, thunderstorms, or hailstorms. |
cumulonimbus (ky m'yə-lō-nĭm'bəs) Pronunciation Key
Plural cumulonimbi (ky m'yə-lō-nĭm'bī)
An extremely dense, vertically developed cloud with a low, dark base and fluffy masses that tower to great heights. Cumulonimbus clouds usually produce heavy rains, thunderstorms, or hailstorms. Also called thundercloud. See illustration at cloud. |