To quash a rebellion or protest means to stop it, often in a violent way. Troops were displaying an obvious reluctance to get involved in quashing demonstrations. To set aside or annul, especially by judicial action. To put down or suppress forcibly and completely: quash a rebellion
put down by force or intimidation; "The government quashes any attempt of an uprising"; "China keeps down her dissidents very efficiently"; "The rich landowners subjugated the peasants working the land"
If someone quashes rumours, they say or do something to demonstrate that the rumours are not true. Graham attempted to quash rumours of growing discontent
If a court or someone in authority quashes a decision or judgment, they officially reject it. The Appeal Court has quashed the convictions of all eleven people
To overthrow; vacate; to annul or void a summons, indictment, bindover order or subpoena, quasi judicial -- Authority or discretion vested in an officer whose acts partake of a judicial character