Bidirectional refers to something that is capable of operating or functioning in two directions. It means that it can move, operate, or work in both forward and reverse directions with equal ease and efficiency. In other words, bidirectional describes a system or process where information, data, or signals can be transmitted in either direction without any loss of meaning or functionality. This is often used to describe communication systems such as telephone lines, computer networks, or interfaces that allow for two-way communication between devices.