Remove words from the Firefox dictionary

Martin Brinkmann
Aug 13, 2007
Updated • Aug 16, 2013

Firefox's build in spell checker is a great asset for all users who are using Firefox for research, work or other activities that involve writing.  It does not matter if you update your blog, are a regular contributor to a forum or like to write reviews on travel sites - the spell checker is a tool that you do not want to miss. New words can be added to the Firefox spell checker by right-clicking the word and choosing Add to Dictionary from the menu.

It may have happened to you as well that you have added a word by accident and want that word removed again from the dictionary. This is the case for example if you add a misspelled word to the dictionary file which may be displayed regularly to you afterwards.

Firefox does not offer an obvious way to delete words from its dictionary which can be quite frustrating if you use the misspelled word regularly. All new dictionary words that you add are saved to the file persdict.dat which is located in your Firefox profile folder. The same holds true for Thunderbird as well and probably for all other Gecko engine based applications.

firefox personal dictionary

I suggest you search for the file persdict.dat on your system, close Firefox before you proceed and open the file afterwards in a text editor that is able to save line breaks. Open Office Writer, Microsoft Word, Ultraedit and Wordpad are suitable programs for this. Just make sure you save the file as a plain text document afterwards and that it retains its original extension.

Locate the misspelled word(s) and remove them from the dictionary file. It is also possible to add words to it, just in case you were wondering. Save the file afterwards, the misspelled words are now gone and won't bother you anymore. (credits: FFExtensionGuru)

Update: It is now easier to find your Firefox profile folder. Type about:support in the browser's address bar and hit enter. Click on show folder here near the top and you are taken to the profile folder automatically.


Tutorials & Tips

Previous Post: «
Next Post: «


There are no comments on this post yet, be the first one to share your thoughts!

Leave a Reply

Check the box to consent to your data being stored in line with the guidelines set out in our privacy policy

We love comments and welcome thoughtful and civilized discussion. Rudeness and personal attacks will not be tolerated. Please stay on-topic.
Please note that your comment may not appear immediately after you post it.