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

Interlisp

    A dialect of Lisp developed in 1967 by Bolt,
   Beranek and Newman (Cambridge, MA) as a descendant of
   BBN-Lisp.  It emphasises user interfaces.  It is
   currently[?] supported by Xerox PARC.

   Interlisp was one of two main branches of LISP (the other
   being MACLISP).  In 1981 Common LISP was begun in an
   effort to combine the best features of both.  Interlisp
   includes a Lisp programming environment.  It is dynamically
   scoped.  LAMBDA functions evaluate their arguments, NLAMBDA
   functions do not.  Any function could be called with optional
   arguments.

   See also AM, CLISP, Interlisp-10, Interlisp-D.

   ["Interlisp Programming Manual", W. Teitelman, TR, Xerox Rec
   Ctr 1975].

   (2004-05-07)