Definition: Reentrancy is a phenomenon in which an object that has been removed from one location enters another. It occurs when an object, such as a car or a building, returns to its original location after being moved or relocated from one point to another. This concept refers to the movement of objects between different locations without them being physically displaced. Reentrancy is often used in computer graphics and robotics to model complex systems where objects can be reentered from their original locations. It helps in understanding how objects