1. The number of degrees that the front wheels can be turned from straight ahead before they are physically restrained from turning any further. Generally, the more lock designed into the front geometry, the smaller the turning circle but the more the tires scrub as the wheels approach the extreme lock positions. Turns lock-to-lock refers to the number of rotations of the steering wheel required to go from one extreme lock position to the other. 2. Can also refer to the locking mechanism usually contained in the steering column that locks the steering wheel when the ignition switch is turned off or the key is removed from the switch.
3. A lock on a motorcycle which prevents the front wheel from being turned left or right.