1. In anatomy, the drum of the ear, the eardrum, the tympanic membrane. The tympanum resembles the head of a tiny drum which separates the middle ear from the external ear.
2. A large hemispherical brass or copper percussion instrument with a drumhead that can be tuned by adjusting the tension on it.
3. The main cavity of the ear; between the eardrum and the inner ear.
4. A vibrating membrane in some insects that serves as a hearing organ.
5. Etymology: the Latin term tympanum auris was introduced by Albertus Magnus, circa A.D. 1225.

A tympanum was a drum or similar instrument; such as, a tambourine or timbrel; also, the stretched membrane of a drum, a drum-head.

"Drum of the ear," A.D. 1619, from Middle Latin tympanum, was introduced in this sense by Itaian anatomist Gabriele Fallopio (A.D. 1523-62), from Latin tympanum "drum" from Greek tympanon, "a drum, a panel of a door", from the root of typtein, "to beat, to strike".