Definition
A 'tin hat' is an informal and sometimes derisive term for a helmet, especially one perceived as flimsy or inadequate. It can also refer to a makeshift hat made of tin. Often, it's used humorously to describe something offering poor protection or a ridiculous piece of headgear. Sometimes the term implies a person is eccentric or paranoid. Think of it as the opposite of a high-tech, effective helmet, more like something out of a cartoon.