Other forms: amerced; amercing
To amerce is to impose a fine on someone as punishment. During the Middle Ages, the King might amerce you if you trespassed on his land to retrieve a lost ball.
The word amerce was more common in medieval times, although it's still used in a legal context, along with amercement. Today when a court amerces someone, it legally orders them to pay a fine after finding them guilty of wrongdoing. The word comes from the French a merci, or "at the mercy," referring to the fact that a person facing amercement is at the mercy of the court.