recursion

Etymology

Borrowed from Latin recursiō (“the act of running back or again, return”), from recurrō (“run back; return”), from re- (“back, again”) + currō (“run”).

noun

1. The act of recurring.
   The inhabitants predicate the recursion of these storms by numerous other signs, and are prompt to take every precaution to avoid their effects. 1852, William Hastings Macaulay, chapter XIX, in Kathay: A Cruise in the China Seas
2. (mathematics) 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.
   However, we have still not achieved our goal of devising a finite set of rules which will generate an infinite set of sentence structures. In order to achieve this goal, we need to allow for the fact that natural languages typically have the property that they allow potentially infinite recursion of particular structures. 1988, Andrew Radford, Transformational grammar: a first course, Cambridge, UK: Cambridge University Press, page 128
3. (programming) The invocation of a procedure from within itself.
   This function uses recursion to compute factorials.
   When an algorithm makes two recursive calls, we say that it uses binary recursion. 2011, Michael T. Goodrich, Roberto Tamassia, David M. Mount, Data Structures and Algorithms in C++, John Wiley & Sons, page 144