- noun a loud noise made by the shock waves produced by an object such as an aircraft or a bullet travelling through the air at or faster than the speed of sound
- noun a noise, due to shock waves, produced when an aircraft travels through the air faster than the speed of sound
- The loud and explosive sound heard when an object or medium exceeds the speed of sound. The sound heard is a result of the shock waves emanating from said object or medium. An aircraft traveling above the speed of sound will produce shock waves, as does the explosive expansion of the air surrounding a lightning discharge. The latter is referred to as thunder.