MS Word: How to disable spell/grammar checking on a custom style

Solution 1:

  1. Right click on the style in the Quick Style Gallery
  2. Click on Modify
  3. In the bottom left corner of the popup click on the Format menu
  4. Click on Language
  5. Select the check box "Do not check spelling or grammar" (be sure to select a language first!)
  6. Click OK on the Language dialog box
  7. Click OK on the Modify Style dialog box

The spell checking will not immediately disappear. But new words you create in that style will not be checked. Restarting Word works too.