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

Stack Environment Control Dump machine
SECD machine

   (SECD machine) The first abstract machine for reducing
   lambda-calculus expressions, invented by P. J. Landin.  The
   machine has four registers holding pointers to linked
   lists operated as push-down stacks which hold the
   information required for the evaluation of an expression.  The
   registers point to (1) Stack which holds the arguments of
   partially evaluated expressions and results of completely
   evaluated ones, (2) Environment where the current expression
   being evaluated is stored, (3) Control which holds the machine
   instructions that manipulate the contents of the four
   registers that represent the expression being evaluated, (4)
   Dump on which the state of the machine is temporarily saved
   during the evaluation of expressions.  See also Lispkit.