The Free On-line Dictionary of Computing (30 December 2018):

Pop-11

    A programming language created by Robin Popplestone
   in 1975, originally for the PDP-11.  Pop-11 is
   stack-oriented, extensible, and efficient like FORTH.  It
   is also functional, dynamically typed, interactive, with
   garbage collection like LISP, and the syntax is block
   structured like Pascal.

   ["Programming in POP-11", J. Laventhol ,
   Blackwell 1987].

   AlphaPop is an implementation for the Macintosh from
   Computable Functions Inc.  PopTalk and POPLOG from the
   University of Sussex are available for VAX/VMS and most
   workstations.

   E-mail: Robin Popplestone 

   (2003-03-25)