subsonic

Etymology
From.

Adjective

 * 1)  having a frequency too low to be audible
 * 2)  very quiet, almost inaudible
 * The noise of the ship was all around her. The faint subsonic rumble of the reactor and drive. (Leviathan Wakes, James S. A. Corey)
 * 1)   less than the speed of sound (in the same medium, and at the same temperature and pressure)
 * 2)  with a Mach number such that 0.3 < Ma < 0.8 (approximately - the exact limits vary between sources)

Translations

 * Bulgarian: дозвукова (скорост)
 * Chinese:
 * Mandarin: 次音速
 * Czech: ,
 * Dutch:
 * Irish: foshonach
 * Italian:
 * Portuguese: subsónico, subsônico
 * Romanian:
 * Russian:
 * Spanish:
 * Swedish: subsonisk, underljuds-
 * Tagalog: kubnugin

Noun

 * 1) an aircraft whose maximum speed is less than the speed of sound

Etymology
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