tympanum in WordNet English dictionary

1. the membrane in the ear that vibrates to sound
   eardrum  tympanum  tympanic membrane  myringa 
   
2. a large hemispherical brass or copper percussion instrument with a drumhead that can be tuned by adjusting the tension on it
   kettle  kettledrum  tympanum  tympani  timpani 
   
3. the main cavity of the ear; between the eardrum and the inner ear
   middle ear  tympanic cavity  tympanum