jet ski noun 1verb 1forms 4 noun1 •A small motorized watercraft with a flattish hull and an upright centre, which a rider sits astride."Jet ski" is actually Kawasaki's name for their PWC (personal water craft) models, but like hoovers and speedos has become genericised. — 2006 verb1 •To ride on a jet ski. formsjet skied · jet skiing · jet skis · jet-skis