"Closed loop" refers to a system where the output of a process is fed back to its input to continuously improve its performance. Synonyms for "closed loop" include "feedback loop," "control loop," "circular process," and "reciprocal system." These terms are often used in fields such as engineering, biology, and economics to describe systems that self-regulate and adjust. In a feedback loop, the output of a system is used to modify its input, creating a loop that allows for continuous improvement over time. Similarly, in a control loop, the output of a system is monitored and adjusted to maintain a desired state. Whether it's called a closed loop, feedback loop, or control loop, the concept remains the same: a system that is self-regulating and constantly improving.