euphonium

[ yoo-foh-nee-uh m ]

/ yuˈfoʊ ni əm /

a brass musical instrument similar to the baritone tuba but somewhat smaller, with a wider bore and mellower tone, and often having a second bell.

Origin of euphonium

First recorded in 1860–65; euph(ony) + (harm)onium

Perhaps the most remarkable place in which a burglar carried his tools was a euphonium!

The Strand Magazine, Vol. VII, Issue 39, March 1894 |Various
The bombardon in B flat or C, an octave lower than the euphonium, corresponds to the contrabass tuba in the orchestra.

Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 2 |Various
The euphonium speaks readily in the lower register, but slowly, of course, owing to the long dip of the pistons.

Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 8 |Various
The euphonium gives out the fundamental, or first note of the harmonic series, readily, but no harmonic above the eighth.

Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 8 |Various

The pitch of the helicon is an octave below that of the euphonium.

Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 |Various

euphonium

/ (juːˈfəʊnɪəm) /

a brass musical instrument with four valves; the tenor of the tuba family. It is used mainly in brass bands

C19: New Latin, from euph ( ony + harm) onium