1.nounA musical instrument in the brass family, having a cylindrical bore, and usually a sliding tube (but sometimes piston valves, and rarely both). Most often refers to the tenor trombone, which is the most common type of trombone and has a fundamental tone of B♭ˌ (contra B♭).
"Jim plays the trombone very well."
2.nounThe common European bittern.
3.verbTo transmit a signal or data back to a central switching point before sending it out to its destination.
4.verbTo extend and retract (the zoom lens); to use it too enthusiastically.