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

dynamic scope
dynamically scoped
dynamic scoping

    In a dynamically scoped language, e.g. most
   versions of Lisp, an identifier can be referred to, not
   only in the block where it is declared, but also in any
   function or procedure called from within that block, even if
   the called procedure is declared outside the block.

   This can be implemented as a simple stack of (identifier,
   value) pairs, accessed by searching down from the top of stack
   for the most recent instance of a given identifier.

   The opposite is lexical scope.  A common implementation of
   dynamic scope is shallow binding.

   (1996-07-11)