rpn

from The Free On-line Dictionary of Computing (8 July 2008)
postfix notation
postfix syntax
Reverse Polish Notation
reverse polish syntax
RPN

   <language> (Or "Reverse Polish Notation", RPN) One of the
   possible orderings of {functions} and {operands}: in postfix
   notation the functions are preceded by all their operands.
   For example, what may normally be written as "1+2" becomes "1
   2 +".  Postfix notation is well suited for {stack} based
   {architectures} but modern {compilers} reduced this advantage
   considerably.

   The best-known language with postfix syntax is {FORTH}.  Some
   {Hewlett-Packard} calculators use it, e.g. HP-25, HP-29C,
   HP-41C, HP-23SII.

   Compare: {infix notation}, {prefix notation}.

   (2003-06-23)