In a vehicle suspension, roll moment is the moment of inertia of the vehicle's sprung mass (the portion of its weight supported by the suspension). The roll moment is the product of the sprung mass and the square of the distance between the vehicle's roll center and its center of mass. If the vehicle is subjected to centrifugal forces, such as in a turn, the roll moment will cause the body to rotate (lean) towards the outside of the turn.
In aeronautics, the roll moment is the aerodynamic force applied at a distance from an aircraft's center of mass that causes the aircraft to undergo angular acceleration about its roll axis, which is usually defined as the longitudinal axis. A roll moment can be the result of wind gusts, control surfaces such as ailerons, or simply by flying at an angle of attack. See flight dynamics.