Dud

A dud is in general something that fails to function in the way it is intended to. In a military context the word is often used to refer to an ammunition round or explosive that fails to fire or detonate as expected. Poorly designed devices (for example, improvised explosive devices (IEDs), shoddy workmanship at the munitions factory, over-complicated fuses, and small devices), have higher chances of being duds. They must be deactivated and disposed of carefully. In war-torn areas, many curious children have been injured or killed from tampering with such devices.

The variation absolute dud describes a nuclear weapon that fails to explode. (A nuclear weapon which does explode, but does not achieve its expected power, is termed a fizzle.)