water cannon
noun [ C ] uk/ˈwɔː.tə ˌkæn.ən/ us/ˈwɑː.t̬ɚ ˌkæn.ən/ water cannons or water cannon
（用于驱散人群的）高压水炮
a device that sends out a powerful stream of water and is used in order to make large groups of people move away
Police used water cannons to break up the demonstration. 警察用高压水炮驱散示威人群。