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

Lisp Machine
MIT Lisp Machine

   1.  Any machine (whether notional or actual)
   whose instruction set is Lisp.

   2.  A line of workstations made
   by Symbolics, Inc. from the mid-1970s (having grown out of
   the MIT AI Lab) to late 1980s.  All system code for
   Symbolics Lisp Machines was written in Lisp Machine Lisp.
   Symbolics Lisp Machines were also notable for having had
   space-cadet keyboards.

   [More details and historical background?]

   Lisp Machine Museum

(http://kogs-www.informatik.uni-hamburg.de/~moeller/symbolics-info/symbolics.html).

   (2003-07-03)