Source : Free On-Line Dictionary of Computing

memo function
     
         (Or "memoised function") A {function} that
        remembers which {arguments} it has been called with and the
        result returned and, if called with the same arguments again,
        returns the result from its memory rather than recalculating
        it.
     
        Memo functions were invented by Professor {Donald Michie} of
        {Edinburgh University}.  The idea was further developed by
        {Robin Popplestone} in his {Pop2} language long before it was
        ever worked into LISP.
     
        This same principle is found at the hardware level in computer
        architectures which use a {cache} to store recently accessed
        memory locations.
     
        A {Common Lisp} package by Marty Hall
        
        {(ftp://archive.cs.umbc.edu/pub/Memoization)}.
     
        ["'Memo' functions: and machine learning", Donald Michie,
        Nature, 218, 19-22, 1968].
     
        (2002-07-02)