Definition of percussions:
(n) :
(music) The section of an orchestra or band containing percussion instruments; such instruments considered as a group; in bands, may be separate from drum kits.
(n) :
(countable) The collision of two bodies in order to produce a sound.
(n) :
(countable) The sound so produced.
(n) :
(countable) The detonation of a percussion cap in a firearm.
(n) :
(engineering) The repeated striking of an object to break or shape it, as in percussion drilling.
(n) :
(medicine) The tapping of the body as an aid to medical diagnosis.