a musical wind instrument consisting of a cylindrical metal tube expanding into a bell and bent twice in a U shape, usually equipped with a slide (slide trombone).
trom·bone (trŏm-bōn', trəm-, trŏm'bōn') n. A brass instrument consisting of a long cylindrical tube bent upon itself twice, ending in a bell-shaped mouth, and having a movable U-shaped slide for producing different pitches.
[French, from Italian, augmentative of tromba, trumpet, of Germanic origin.] trom·bon'ist n.
A brass instrument; the player can change its pitch by sliding one part of the tube in and out of the other. The tone of the trombone is mellower than that of the trumpet.