Source : Webster's Revised Unabridged Dictionary (1913)

Recursion \Re*cur"sion\ (-sh?n), n. [L. recursio. See {Recur}.]
   The act of recurring; return. [Obs.] --Boyle.

Source : WordNet®

recursion
     n : (mathematics) an expression such that each term is generated
         by repeating a particular mathematical operation

Source : Free On-Line Dictionary of Computing

recursion
     
         When a {function} (or {procedure})
        calls itself.  Such a function is called "recursive".  If the
        call is via one or more other functions then this group of
        functions are called "mutually recursive".
     
        If a function will always call itself, however it is called,
        then it will never terminate.  Usually however, it first
        performs some test on its arguments to check for a "base case"
        - a condition under which it can return a value without
        calling itself.
     
        The {canonical} example of a recursive function is
        {factorial}:
     
        	factorial 0 = 1
        	factorial n = n * factorial (n-1)
     
        {Functional programming languages} rely heavily on recursion,
        using it where a {procedural language} would use {iteration}.
     
        See also {recursion}, {recursive definition}, {tail recursion}.
     
        [{Jargon File}]
     
        (1996-05-11)