Learn how to say Trombonist correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word trombone:
a large brass wind instrument with straight tubing in three sections, ending in a bell over the player’s left shoulder, different fundamental notes being made using a forward-pointing extendable slide.
an organ stop with the quality of a trombone.
early 18th century: from French or Italian, from Italian tromba ‘trumpet’