define hoist on his own petard?

What does the expression he was hoist on his own petard mean?

A petard is an old-fashioned bomb. If you look up Petard on the wikipedia you will find a section devoted to the phrase: If a petard detonated prematurely, the petardier would be lifted by the explosion. In addition, the usual human response is to get away from trouble by the most direct means possible, but a straight line is rarely the safest route of departure while under fire, and this is particularly true after setting a petard. The backblast went straight back from the fortification: if the petardier also moved straight back he would be hoist by his own petard. William Shakespeare used hoist with his own petard in Hamlet, in which the word hoist is the (now archaic) past participle of the earlier form hoise for the verb hoist.[3][4]

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I would gladly tell you what it means, it means injured by the device that you intended to use to injure others.