cavity vs tooth decay

cavity and tooth decay both are nouns.

Word	Noun	Adjective	Verb	Adverb
cavity	Yes	No	No	No
tooth decay	Yes	No	No	No

As nouns, cavity and tooth decay are synonyms defined as:

cavity and tooth decay: soft decayed area in a tooth; progressive decay can lead to the death of a tooth

Other synonyms of cavity include caries, dental caries.

cavity (noun)	tooth decay (noun)
(anatomy) a natural hollow or sinus within the body	soft decayed area in a tooth; progressive decay can lead to the death of a tooth
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