The ophicleide is a family of conical-bore keyed brass instruments invented in early 19th-century France to extend the keyed bugle into the alto, bass and contrabass ranges. Of these, the bass ophicleide in C or B♭ took root over the course of the 19th century in military bands and as the bass of orchestral brass sections throughout Western Europe, replacing the serpent and its later upright derivatives. By the end of the 19th century however, it had been largely superseded by early forms of the modern tuba, developed from valved ophicleides.

A brass instrument is a musical instrument that produces sound by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips. Brass instruments are also called labrosones or labrophones, from Latin and Greek elements meaning 'lip' and 'sound'.