Noun | 1. | tuba - the lowest brass wind instrument bass horn, sousaphone bass - the member with the lowest range of a family of musical instruments brass instrument, brass - a wind instrument that consists of a brass tube (usually of variable length) that is blown by means of a cup-shaped or funnel-shaped mouthpiece euphonium - a bass horn (brass wind instrument) that is the tenor of the tuba family bombardon, helicon - a tuba that coils over the shoulder of the musician |