Recursion

noun

1. The act of recurring.
2. The act of defining an object (usually a function) in terms of that object itself.

   "n! = n × (n − 1)! (for n > 0) or 1 (for n = 0) defines the factorial function using recursion."

3. The invocation of a procedure from within itself.

   "This function uses recursion to compute factorials."