The circle traced by the front outside wheel of the vehicle when it is turned to the full lock of its steering mechanism. (See also Minimum Turning Radius)

the circle made by a ship when the rudder is put over; one of the standard manoeuvre that serves as a measure of manoeuvrability of ships; a number of parameters are used to define the turning performance, for example, diameter of the steady turning circle, turning rate, steady speed on turn, etc.

Typically measured curb-to-curb, this is the tightest possible circle driven by the outside front tire between two imaginary curbs.