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

denotational semantics

    A technique for describing the meaning of programs in
   terms of mathematical functions on programs and program
   components.  Programs are translated into functions about
   which properties can be proved using the standard mathematical
   theory of functions, and especially domain theory.

   Compare axiomatic semantics, operational semantics,
   standard semantics.

   (1996-08-21)