waterheaded adjective3 •Hydrocephalic.Lolek, the market boy, a waterheaded child of five, crawled among the wilted cabbage leaves and dead-eyed fishheads nodding his monstrous head to the shrill voice of the nun. — 1988 •(slang, offensive) Stupid or ugly.Kahlem's not a bad Watchman , ” Renaer said , “ but his waterheaded ideas on how to investigate crimes–" — 2008 •Filled with waterheads. formsmore waterheaded · most waterheaded