The euphonium is a medium-sized, 3 or 4-valve, often compensating, conical-bore, tenor-voiced brass instrument that derives its name from the Ancient Greek word εὔφωνος euphōnos, meaning "well-sounding" or "sweet-voiced" (εὖ eu means "well" or "good" and φωνή phōnē means "sound", hence "of good sound"). The euphonium is a valved instrument. Nearly all current models have piston valves, though some models with rotary valves do exist.