On wheeled or tracked vehicles, body roll is a reference to the load transfer of a vehicle towards the outside of a turn. When a vehicle is fitted with a suspension package, it works to keep the wheels or tracks in contact with the road, providing grip for the driver of the vehicle to control its direction. This suspension is compliant to some degree, allowing the vehicle body, which sits upon the suspension, to lean in the direction of the perceived centrifugal force acting upon the car. Anti-roll bars are a part of the suspension specifically designed to address body roll.
When a vehicle is fitted with a suspension there is compliance between the mass of the vehicle and the vehicle's contact with the ground. Body roll is the noticeable (either perceived or measurable) deflection produced when load transfer acts on the compliant elements of the suspension. Anti-roll bars directly impact body roll but their design intent is actually as a tool to adjust roll couple percentage or roll moment distribution.