A bi-stable device is a device that is like a switch because it can be in only two possible stable states. Bistable devices follow the principle of bistability and are foundation of digital electronics.
Bistable device definition
A bistable device is a device that can be either in one of the two possible states such as on or off, pulse or no pulse, 0 or 1.
Transistors, flip-flop and organic bistable devices are examples of bistable device.