necking knob
dated A rounded knob mounted to the steering wheel of a car so that it can be steered with one hand. So called because the driver (typically male) is able to place their arm around their romantic partner. My grandfather gave me his old Cadillac, which still had the necking knob on the wheel from when he first started courting my grandmother.
necking knob
A swivel on a car's steering wheel. The necking knob enables the driver to steer with his left hand while encircling his girlfriend's shoulder with his right arm. Even when the driver was alone, the knob was an easy way to turn the car in the days before power steering.