1. a type of bullet designed to expand on impact
Usage: military; firearms
2. a foolish or stupid person
Usage: informal; sometimes offensive

Examples

• The dumdum bullet was banned by international treaty.
• Military historians studied the effects of dumdum ammunition.
• Don’t be such a dumdum about this simple problem.
• He felt like a dumdum after making that obvious mistake.
• The treaty prohibited the use of dumdum bullets in warfare.
• She called him a dumdum for forgetting his keys again.