What is the name for yaw stability?

Yaw stability is referred to as directional stability. This type of stability relates to the aircraft's ability to maintain or return to its original heading following a disturbance, such as external forces or control inputs. When an aircraft has good directional stability, it effectively minimizes unwanted yaw movements, allowing it to maintain a straight flight path with less pilot intervention.

In the context of aircraft dynamics, directional stability ensures that the aircraft can resist yawing motions and return to a neutral position after being disturbed. This is crucial for the safe and controlled handling of the aircraft, enhancing its overall performance. The design features contributing to directional stability typically include the vertical stabilizer and the rudder, which work together to maintain alignment with the intended flight direction.

While other forms of stability are critical for an aircraft's overall behavior—such as longitudinal stability (related to pitch and the aircraft's ability to maintain its angle of attack) and lateral stability (concerned with roll control)—they do not specifically pertain to yaw stability, which is why directional stability is the correct term in this context.