A dud is an object or performance that fails to work properly or is unimpressive.
When we call something a dud, we usually mean it's not doing its job well. This can happen with things like fireworks, which should make a big noise but just fizzle out instead. It can also be used for jokes, movies, or other performances that don't quite hit the mark. Imagine you go to see a comedian and they bomb – their jokes fall flat, and everyone looks disappointed. That's when we'd say the comedy show was a dud.
(informal) A device or machine that is useless because it does not work properly or has failed to work, such as a bomb, or explosive projectile.
