ispell-local-pdict

ispell-local-pdict is a variable defined in `ispell.el'.
Its value is

nil

• Automatically becomes buffer-local when set.
• This variable is safe as a file local variable if its value
  satisfies the predicate `stringp'.

Documentation:
A buffer local variable containing the current personal dictionary.
If non-nil, the value must be a string, which is a file name.

If you specify a personal dictionary for the current buffer which is
different from the current personal dictionary, the effect is similar
to calling M-x ispell-change-dictionary. This variable is automatically
set when defined in the file with either `ispell-pdict-keyword' or the
local variable syntax.