Category:Tympanum

Tym"pa*num, n.; pl. E. Tympanums, l. Tympana. Etym: [l., a Kettledrum, a drum or wheel in machines, the triangular area in a Pediment, the panel of a door, gr. Type, and cf. Timbrel.]

1. (anat.) (a) the ear drum, or middle ear. Sometimes applied incorrectly to the Tympanic membrane. See ear. (b) a chamber in the anterior part of the syrinx of birds.

2. (zoöl.)

Defn: one of the naked, inflatable air sacs on the neck of the Prairie chicken and other species of grouse.

3. (arch.) (a) the recessed face of a pediment within the frame made by the Upper and lower cornices, being usually a triangular space or table. (b) the space within an arch, and above a lintel or a subordinate Arch, spanning the opening below the arch.

4. (mech.)

Defn: 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.