Definition - What does Circular Reference mean?
A circular reference in computer programming is a situation in which two values reference each other. This type of reference can be extremely problematic if two functions or values depend on one another for definition. This term is used in the IT world much like it is in general language to refer to when one thing references another and vice versa.
Techopedia explains Circular Reference
A circular reference is also problematic in programming, and may occur where a function returns a given result that is used by another function to return the same result. In some cases, this will simply provide useless code. In other situations, it may create a deadlock or crash a program.