waterboard noun 2verb 1forms 3 noun2 •A public commission charged with overseeing water quality in a particular area.The waterboard argued that the quality of the water was good […] — 2005 •A board set up to windward in a boat, to keep out water. verb1 •To subject to waterboarding, to pour water over a cloth covering the face and breathing passages of an immobilized captive.We waterboarded the suspect, but he refused to confess. formswaterboarded · waterboarding · waterboards