A small bell-shaped bomb used to breach a gate or wall.(noun)
A loud firecracker.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "petard" in a sentence
"She had meant to try out Jasper's racing-car at dawn, forgetting that racers have no mufflers, and she had been, as one may say, hoist with her own petard – although I do not know what a petard is and have never been able to find out."
"Watching ignorant lefties (didn’t read the law) and/or evil lefties (supporters of illegal entry) hoist with their own petard is very satisfying theater indeed."
"A petard was a small medieval bomb used to blow up gates and walls when breaching fortifications."