A percussion instrument is any object which produces a sound by being hit with an implement, shaken, rubbed, scraped, or by any other action which sets the object into vibration. The term usually applies to an object used in a rhythmic context or with musical intent.

The word "percussion" has evolved from Latin terms: "percussio" (which translates as "to beat, strike" in the musical sense, rather than the violent action), and "percussus" (which is a noun meaning "a beating"). As a noun in contemporary English it is described at Wiktionary as "the collision of two bodies to produce a sound". The usage of the term is not unique to music but has application in medicine and weaponry, as in percussion cap, but all known and common uses of the word, "percussion", appear to share a similar lineage beginning with the original Latin: "percussus". In a musical context then, the term "percussion instruments" may have been coined originally to describe a family of instruments including drums, rattles, metal plates, or wooden blocks which musicians would beat or strike (as in a collision) to produce sound.