quicksand vs cavity

quicksand and cavity both are nouns.

Word	Noun	Adjective	Verb	Adverb
quicksand	Yes	No	No	No
cavity	Yes	No	No	No

As nouns, cavity is a hypernym of quicksand; that is, cavity is a word with a broader meaning than quicksand:

quicksand: a pit filled with loose wet sand into which objects are sucked down
cavity: a sizeable hole (usually in the ground)

Other hypernyms of quicksand include pit.

quicksand (noun)	cavity (noun)
a pit filled with loose wet sand into which objects are sucked down	(anatomy) a natural hollow or sinus within the body
a treacherous situation that tends to entrap and destroy	a sizeable hole (usually in the ground)
	soft decayed area in a tooth; progressive decay can lead to the death of a tooth
	space that is surrounded by something