Euphonium

The euphonium (English: /juˈfoʊiːəm/ yoo-FOH-nee-im; Italian: eufonio; Spanish: bombardino) is a tenor- and baritone-voiced valved brass instrument. The euphonium is a member of the large family of valved bugles, along with the tuba and flugelhorn, characterised by a wide conical bore. Most instruments have three or four valves, usually compensating piston valves, although instruments with rotary valves are common in Eastern and Central Europe.

Euphonium repertoire may be notated in the bass clef as a non-transposing instrument or in the treble clef as a transposing instrument in B♭. In British brass bands, it is typically treated as a treble-clef instrument, while in American band music, parts may be written in either treble clef or bass clef, or both. A musician who plays the euphonium is known as a euphoniumist, a euphonist, or simply a euphonium or "eupho" player.