Cumulonimbus is a type of cloud, similar to cumulus, that extends to a great height and is associated with thunderstorms.
[technical]
cumulonimbus in British English
(ˌkjuːmjʊləʊˈnɪmbəs)
nounWord forms: plural-bi (-baɪ) or -buses
meteorology
a cumulus cloud of great vertical extent, the top often forming an anvil shape and the bottom being dark coloured, indicating rain or hail: associated with thunderstorms
cumulonimbus in American English
(ˌkjumjəˌloʊˈnɪmbəs)
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