Euphonium, German baryton, brass wind instrument with valves, pitched in C or B♭ an octave below the trumpet; it is the leading instrument in the tenor-bass range in military bands. It was invented in 1843 by Sommer of Weimar and derived from the valved bugle (flügelhorn) and cornet.
A person who plays the euphonium is sometimes called a euphoniumist, euphophonist, or a euphonist.
