water-cannon

n machine that produces a powerful jet of water, used eg to disperse a crowd of rioters 水炮（强力喷水器, 如用以驱散暴乱人群的）.

watchdog, watcher, watchful, watchfully, watchfulness, watching brief, watchmaker, watchman, watchword, water, water point, water polo, water ski, water-bed, water-bird, water-biscuit, water-borne, water-bottle, water-buffalo, water-butt, water-closet, water-colour (US -color), water-cooled, water-diviner, water-fowl, water-hammer, water-hole, water-ice, water-jump, water-level, water-lily, water-line, water-main, water-meadow, water-melon, water-mill, water-pistol, water-power, water-rat, water-rate,