Check out Using styles to set spell-check options in Word by Mike Pope<mike@mikepope.com>. Here is an excerpt:
There are many reasons to use styles in Word, as I’ve noted before. One feature I find handy is using styles that have different spell-check options for different types of text. I’ll explain a couple of examples: one where I set a non-default spell-check option (Spanish), and another where I…
The full article is available here.