tympanic cavity vs tympanum

tympanic cavity and tympanum both are nouns.

Word	Noun	Adjective	Verb	Adverb
tympanic cavity	Yes	No	No	No
tympanum	Yes	No	No	No

As nouns, tympanic cavity and tympanum are synonyms defined as:

tympanic cavity and tympanum: the main cavity of the ear; between the eardrum and the inner ear

Other synonyms of tympanic cavity include middle ear.

tympanic cavity (noun)	tympanum (noun)
the main cavity of the ear; between the eardrum and the inner ear	a large hemispherical brass or copper percussion instrument with a drumhead that can be tuned by adjusting the tension on it
	the membrane in the ear that vibrates to sound
	the main cavity of the ear; between the eardrum and the inner ear