petard

noun

1. (historical)A small, hat-shaped explosive device, used to breach a door or wall.

   “For tis the ſport to haue the enginer / Hoiſt with his ovvne petar, an't ſhall goe hard / But I vvill delue one yard belovve their mines, / And blovve them at the Moone: […]”

   “[…] Pipes, who acted as the enemy's forlorn hope, advanced to the gate with great intrepidity, and clapping his foot to the door, which was none of the ſtouteſt, with the execution and diſpatch of a petard, ſplit it into a thouſand pieces.”

2. Anything potentially explosive, in a non-literal sense.
3. (rare)A loud firecracker.

verb

1. (archaic)To attack or blow a hole in (something) with a petard.

   “The Souldier, if he but go to beſiege a cottage, to ſcale a Caſtle, to robbe a Church, to Pettard [translating petarder] a gate, to force a religious houſe, or any villenous act, before he attempt-it, praieth to God for his aſſiſtance, though his intents and hopes be full-fraught with crueltie, murther, couetiſe, luxurie, ſacriledge and all iniquitie.”