thundercloud vs cumulonimbus cloud

thundercloud and cumulonimbus cloud both are nouns.

Word	Noun	Adjective	Verb	Adverb
thundercloud	Yes	No	No	No
cumulonimbus cloud	Yes	No	No	No

As nouns, thundercloud and cumulonimbus cloud are synonyms defined as:

thundercloud and cumulonimbus cloud: a dark cloud of great vertical extent charged with electricity; associated with thunderstorms

Other synonyms of thundercloud include cumulonimbus.

thundercloud (noun)	cumulonimbus cloud (noun)
a dark cloud of great vertical extent charged with electricity; associated with thunderstorms	a dark cloud of great vertical extent charged with electricity; associated with thunderstorms