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

local variable

    A variable with lexical scope, i.e. one
   which only exists in some particular part of the source
   code, typically within a block or a function or
   procedure body.  This contrasts with a global variable,
   which is defined throughout the whole program.

   Code is easier to understand and modify when the scope of
   variables is as small as possible because it is easier to see
   how the variable is set and used.  Code containing global
   variables is harder to modify because its behaviour may depend
   on and affect other sections of code that refer to that
   variable.

   (2009-12-14)