a form of torture, typically used as an interrogation technique, in which a person is strapped head-down on a sloping board with the mouth and nose covered while water is poured over their face, causing them to experience a sensation similar to that of drowning

his lawyers told the court that he was subjected to waterboarding on more than 80 occasions

subject (someone) to the process of waterboarding

he was waterboarded and deprived of sleep