dud

The word "dud" is used for something that fails, does not work, or turns out to be disappointing. It often describes an object that was supposed to do something but did not. You might use it for a firework that never goes off, a machine that stops working almost at once, or a movie that looked exciting but was disappointing.

It is especially common in the language of explosives. A bomb or shell that fails to explode is called a "dud," and that meaning is still widely recognized. From there, the word is also used more generally for anything that does not deliver what people expected.

People also use it in informal speech for performances, plans, jokes, or products. If someone says a party was a dud, they mean it was flat and disappointing. If they say a new gadget was a dud, they mean it was useless or broken. In some contexts, it can also describe a person, suggesting that the person is dull, ineffective, or unimpressive, but that use can sound rude.

Overall, the word suggests failed expectations. Something looked like it might be good, useful, or exciting, but in the end it did not deliver.