Noun
Any musical instrument which produces sound primarily by causing a body of air to vibrate, without the use of strings or membranes, and without the vibration of the instrument itself adding considerably to the sound.
(dated) A form of combined speaking trumpet and ear trumpet.
(dated) An instrument for greatly intensifying speech, consisting of a phonograph diaphragm arranged so that its action opens and closes valves, producing synchronous air blasts sufficient to operate a larger diaphragm with greater amplitude of vibration.
Source: en.wiktionary.org