Add words to Firefox’s spell-check dictionary

When you type something in a form (text box) on a web site, Firefox automatically performs the spell check using an in built dictionary. When you type a wrong word, it underlines the mis-spelled word with a wavy red underline. You can right-click on such a word and use one of the suggestions as shown :

Often it happens that a word is not in the spell-check dictionary. You can always add that word by right clicking on that word and clicking Add to dictionary or you can manually edit the dictionary as shown below :

  1. Open Firefox.
  2. Type about:support in the location bar (where you type web site address).
  3. You would see a page with many sections. On the top, under the Application Basics section click on Open Containing Folder

  4. Close all the open Firefox windows.
  5. In the folder that opens in 3rd step, you would find a file persdict.dat. Open this file in Notepad or any other plain text editor of your choice. This file contains all the words that you added by right-clicking on a mis-spelled word and selecting Add to dictionary. You can manually remove or add new words to this file – one word per line. If this file does not exist, then simply create a file of this name in that folder.

  6. Save this file persdict.dat and start Firefox again. You would find that Firefox does not detect the added words as mis-spelled anymore.