tympanum

Etymology

Borrowed from Latin tympanum (“a drum, timbrel, tambourine; the eardrum”). Doublet of timbre and timpani.

noun

1. (archaic) A drum.
2. (anatomy, zootomy) Any of various anatomic structures in various animals with analogy to a drum head:
   1. (anatomy, zootomy) The eardrum (tympanic membrane, membrana tympanica).
   2. (anatomy, zootomy) The main portion of the middle ear: the tympanic cavity (cavitas tympani).
   3. (zootomy, entomology) A thin tense membrane covering the hearing organ on the leg or body of some insects, sometimes adapted (as in cicadas) for producing sound.
   4. (zootomy) A membranous resonator in a sound-producing organ in frogs and toads.
   5. (zootomy) (in certain birds) The labyrinth at the bottom of the windpipe.
3. (architecture) A vertical recessed triangular space between the sides of a pediment, typically decorated
   1. The recessed triangular space within an arch, and above a lintel or a subordinate arch, spanning the opening below the arch
4. (engineering) A drum-shaped wheel with spirally curved partitions by which water is raised to the axis when the wheel revolves with the lower part of the circumference submerged; used for raising water, as for irrigation.