Plain English Meaning

Springs inside the airplane that link the ailerons and rudder so that when you bank into a turn, a little rudder is automatically applied for you. It makes the airplane easier to fly in coordinated turns without having to push the rudder pedals as much.

Full Definition

A mechanical linkage of springs that connects the aileron control system to the rudder control system, automatically applying a small amount of rudder deflection in the same direction as aileron input. This coupling helps coordinate turns by reducing the rudder pedal pressure the pilot must apply to counter adverse yaw.