The story
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A hybrid trombone having both a set of three piston valves and a slide to vary the pitch, the slide being positioned within the valve section and shorter than a standard trombone slide, only covering four positions instead of the usual seven, and not locking. Full definition →
Etymology from Wiktionary, CC BY-SA 4.0.