The drum or eardrum.
Greek tumpanon, drum.
The literal Greek sense survives in English timpani or tympani for kettledrums, especially when played by one musician in an orchestra. The stretched membrane of a drum, the drumhead, is the tympanum.
This word was borrowed into anatomy in the seventeenth century as a formal term for the eardrum; another name for it is the tympanic membrane. Linked terms include tympanoplasty, the surgical repair of defects of the eardrum or the ossicles of the middle ear; tympanometry, the measurement, for diagnostic purposes, of changes in the compliance of the tympanic membrane as the air pressure is altered in the passage of the external ear, leading to the production of a tympanogram, a graphical record of the pressure changes; and tympanosclerosis is thickening of the tympanic membrane, and of the connective tissue in the tympanic cavity. See also myringo‑.
However, the condition called tympanides is swelling of the abdomen with air or gas so that it becomes resonant or drumlike.