Wiktionary
alt. An activity, usually involving children, where the participants use water balloons, water gun and water pistol to get each other wet. n. An activity, usually involving children, where the participants use water balloons, water gun and water pistol to get each other wet.
Wikipedia
A water fight is a type of mock combat using various water-dispensing devices to soak opponents. Everything from buckets to balloons to water guns and even cupped hands cradling water can be applied in a water fight. There are many different levels of game play used by those engaging in water fights, from quick, casual fights to long, objective-oriented-style water warfare campaigns, and tournament-style games. In most but not all cases, the common objective is to soak (spray with water) one's opponents while trying to remain dry.
Usage examples of "water fight".
They bounced off their ponies and jumped into the trough for a water fight.
She heard muffled laughter and splashes that hinted at a water fight, and smiled.
There was a concerted rush into the sea and then they began a water fight.
He had been staring at Viridovix's back and shoulders when the Gaul turned them during the water fight.
Down on the torpedo deck Pig and Lazar were having a water fight, chasing each other among the gray tubes now highlighted vermilion by the sunset.
When she did so, when she quit the water fight and stooped in her wet garments above him, the entire story, which is all told by that same little brother in the first section, seemed to explode on the paper before me.
He smiled at the doctor's description of the water fight, but he was disturbed by the drawn quality of Beverly Crusher's face.