Petard is a word that survives in the modern world entirely in the expression hoist with his own petard, which means someone fails because of their own plans or because of their own deviousness. It is usually understood that its literal meaning is to be blown up with your own bomb. But there is a far more comical interpretation.

The expression is one of Shakespeare's most descriptive—he used it in Hamlet III.iv.207 in 1605.

For tis the sport to haue the enginer Hoist with his owne petard.

The word, petard, in English, comes from the late 16th century and was used for a small cannon-like bomb used to blow in doors and breach walls. The English borrowed the word directly from the French who had coined the word  pétard for this type of bomb. The bomb was made by filling a thick metal cannister with gunpowder, setting it against the wall or door to be breached  and then exploding it by lighting a wick. Petards were quite unreliable and often exploded prematurely "hoisting" the engineer setting it alight high into the air.

Petard has a rather humorous ancestry having been derived from the Middle French word péter, which meant to break wind, from Old French pet, which originally came from Latin, pedere to break wind. The bomb got its name because its sound was fart-like.

When I first came across the expression—learning Shakespeare in my English lessons—I was very much impressed with the metaphor. However, I still cannot forgive that English teacher for not explaining that Shakespeare, who loved his puns and his double entendres, was probably also suggesting that the engineer was blown up by his own fart. This would have given the schoolboy me a much greater love and appreciation of Shakespeare than I had at the time.

For more words of the week visit my site.