Source : Free On-Line Dictionary of Computing

ZetaLisp
     
         The {Maclisp} dialect used on the {LISP Machine}.
        The many extensions to Maclisp include {vectors}, {closures},
        {flavors}, {stack groups}, {locatives}, and {invisible
        pointers}.  Currently supported by {Lisp Machines, Inc.} and
        {Symbolics}.
     
        ["LISP Machine Manual", D. Weinreb and D. Moon, MIT AI Lab,
        1981].
     
        (1997-03-18)