slang One who drives excessively or dangerously fast in a car. The phrase is based on the expression "have a lead foot," meaning to have a tendency to speed when driving. The image is that of one's foot being made of lead, which is very heavy, and thus pushing down on the accelerator. I've always been a bit of a Larry Leadfoot when I get behind the wheel, so I've gotten my fair share of speeding tickets. Some Larry Leadfoot went flying past me on the interstate and nearly careered into a truck.