volcano vs cleft

volcano and cleft both are nouns.

Word	Noun	Adjective	Verb	Adverb
volcano	Yes	No	No	No
cleft	Yes	Yes	No	No

As nouns, cleft is a hypernym of volcano; that is, cleft is a word with a broader meaning than volcano:

volcano: a fissure in the earth's crust (or in the surface of some other planet) through which molten lava and gases erupt
cleft: a long narrow cleft

Other hypernyms of volcano include crack, crevice, fissure, scissure.

volcano (noun)	cleft (noun)
a mountain formed by volcanic material	a long narrow cleft
a fissure in the earth's crust (or in the surface of some other planet) through which molten lava and gases erupt	a split or indentation in something (as the palate or chin)

volcano (adjective)	cleft (adjective)
	having one or more indentations reaching nearly to the midrib
	split or divided