Trombone :: Trombone (n.) A powerful brass instrument of the trumpet kind, thought by some to be the ancient sackbut, consisting of a tube in three parts, bent twice upon itself and ending in a bell. The middle part, bent double, slips into the outer parts, as in a telescope, so that by change of the vibrating length any tone within the compass of the instrument (which may be bass or tenor or alto or even, in rare instances, soprano) is commanded. It is the only member of the family of wind instruments whos