cumulonimbus

(kyo̵̅o̅′myə lō′nimbəs)

noun

the type of dense cloud that develops vertically through all cloud levels, consisting of water droplets, ice crystals, and sometimes hail, and associated with thunder, lightning, and heavy showers

See cumulonimbus in American Heritage Dictionary 4

cu·mu·lo·nim·bus

noun 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.

Learn more about cumulonimbus

link/cite print suggestion box