(Italian) set of kettledrums. Or kettledrums tuned drums derived from medieval nakers (from Arabic naqqara), each consisting of a single skin stretched over a bowl resonator that tunes and focuses the sound.
Originally used in pairs tuned to the tonic and dominant key, their numbers were increased and mechanisms introduced during the 19th century to allow pitch changes during a performance. The modern instrument is tunable by pedal. A normal symphony orchestra will have up to five timpani, ranging in pitch from about B1 to G3.