A trombone that, when subjected to water or water-based
liquids and even air moisture for a long enough time, develops an outer layer
of iron oxide most commonly
known as rust. It makes
a trombone aesthetically and ergonomically unpleasing, as well
as difficult to play.
Andy: Hey Bobby, do you want to play
Bobby: No, I want to play
my trombone but it's not working. I dropped it in the water and accidentally left it there
for six weeks. Now it is a rusty trombone.