cavity vs quicksand

cavity and quicksand both are nouns.

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

As nouns, quicksand is a hyponym of cavity; that is, quicksand is a word with a more specific, narrower meaning than cavity:

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

Other hyponyms of cavity include trou-de-loup, barbecue pit, borrow pit, divot, fire pit, sandpit, sawpit, tar pit.

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