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

MLISP

   1. M-expression LISP.

   2. Meta-LISP.  D.C. Smith & H. Enea.  LISP variant with
   ALGOL-like syntax.  Not just a surface syntax, a full
   language.

   "MLISP", D.C. Smith, TR CS-179, CS Dept, Stanford (Oct 1970).
   Version: MLISP2.

   3. A hybrid of M-expression LISP and Scheme.

   "M-LISP: Its Natural Semantics and Equational Logic",
   R. Muller, SIGPLAN Notices 26(9):234-242 (Sept 1991) (PEPM
   '91).