brass wind musical instrument with a cup-shaped mouthpiece and padded keys, the bass version of the old keyed bugle. The name (from Greek ophis and kleid, "serpent" and "key") alludes to its improvement on the military band "upright serpents" (now-obsolete S-shaped bass instruments sounded by vibration of the lips against a cup mouthpiece) by providing 11 brass keys to replace open finger holes