The word "quash" is a verb that primarily means to stop something from continuing by doing or saying something. It can also mean to officially declare a previous decision, such as a ruling or verdict, as wrong and no longer valid. In legal contexts, quashing often refers to setting aside or voiding proceedings, motions, or evidence, such as quashing a subpoena or a court verdict. Examples of usage include:

• The police quashed the riot, stopping it from continuing.
• A judge may quash a lower court's verdict, ordering a new trial.
• In general usage, quashing can mean suppressing or extinguishing something completely, like quashing rumors or a rebellion.

The term suggests suppression or nullification, often through authoritative or legal means. It derives from Middle English, originating from Old French "quasser," meaning to annul or smash. In short, to quash is to suppress completely or to officially annul or overturn something, especially in legal contexts. Would you like examples or information on how "quash" is used in specific fields like law?