Final answer:
The phrase 'hoist by one's own petard' means to be harmed by one's own plans meant to harm someone else, originating from Shakespeare's 'Hamlet.' A 'petard' is a small explosive device, and being 'hoist' meant being blown up by it, signifying someone being caught in their own trap.
Step-by-step explanation:
Definition and Origin of 'Hoist with One's Own Petard'
The phrase 'hoist by one's own petard' means to be harmed by one's own plan or actions that were intended to harm someone else. The origin can be traced back to William Shakespeare's play 'Hamlet.' In the text, a 'petard' is a small explosive device used in warfare to breach gates or walls. The term 'hoist' in this context meant to be lifted or thrown into the air by an explosion. Therefore, if someone is 'hoist by his own petard,' it indicates that the individual has been caught in their own trap or has suffered the consequences of their own actions.
This idiom is often used to describe a situation where someone's schemes backfire on them. For example, if a person was trying to sabotage a colleague but ends up getting demoted instead, they could be said to have been 'hoist by their own petard.' The irony inherent in this situation is what gives the expression its force and lasting popularity.