Wiktionary
cimbasso
n. (context musici English) A bass trombone
Wikipedia
Cimbasso
The cimbasso is a brass instrument in the trombone family, with a sound ranging from warm and mellow to bright and menacing. It has three to six piston or rotary valves, a predominantly cylindrical bore, and is usually pitched in C, F or E. It is in the same range as a tuba or a contrabass trombone.
The modern instrument can be played by a tubist or a bass trombonist.
framed|"Bent" cimbasso