Edit Firefox’s Spelling Dictionary

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Edit Firefox’s Spelling Dictionary

Mar 8, 2007 at 8:00pm in How To, Software

If you have used Firefox’s built in dictionary, you will know there is a limitation to it. Firefox allows you to easily add words to dictionary, but lacks a user interface for removing words. This can be a problem since the “Add to dictionary” button is directly under the corrected words, providing easy access for adding misspelled words to the dictionary.

Since I frequently add misspelled words, I had to learn the method for removing these words. To remove misspelled words, first close down Firefox then navigate to your profile folder. The folder’s location varies depending on your operating system:

Windows XP

C:\Documents and Settings\[User Name]\Application Data\Mozilla\Firefox\Profiles\xxxxxxxx.default\

Windows Vista

C:\users\[User Name]\AppData\Roaming\Mozilla\Firefox\Profiles\xxxxxxxx.default\

Mac OS X

~/Library/Application Support/Firefox/Profiles/xxxxxxxx.default/

Linux

~/.mozilla/firefox/xxxxxxxx.default/

Once in your profile folder, look for a file named persdict.dat, and open it with your favorite text editor. Inside you’ll find all of your custom defined words, each on their own line. Just delete the words which don’t belong and save. Firefox will no longer incorrectly identify those misspelled words as correct.

68 Comments

1 Jonathan on Mar 8, 2007 at 8:35 pm:

Neat trick. Maybe knowing this can help make a plug-in?
2 Stephen on Apr 8, 2007 at 5:13 pm:

Thanks for this one. I accidentally added a word to the dictionary that didn’t belong. I really need to watch my click happy finger.
3 firefox user on Apr 17, 2007 at 3:47 am:

Thanks!
4 Amir D on Apr 22, 2007 at 4:19 pm:

Hi,

I’m running OS 10.4.9 and only have a Mozilla folder inside the library folder which contains the file pkcs11.shlb and nothing else… any ideas?

Thanks a lot,
5 Ronald Heft on Apr 22, 2007 at 4:37 pm:

Amir, you should be looking for a Firefox folder, not a Mozilla folder.
6 Amir D on Apr 23, 2007 at 4:07 am:

Thanks for the quick reply.

Trust me, I did. There’s no Firefox folder inside the Application Support folder. I’m more than happy to provide a screenshot
7 Ronald Heft on Apr 23, 2007 at 7:49 am:

You’re looking in your user folder and not the system Application Support, correct?
8 Amir D on Apr 23, 2007 at 2:08 pm:

ooops that did it. Thanks a lot!
9 Crystal on Apr 25, 2007 at 9:07 am:

THANK YOU!!! Man, I click the wrong damn line all the time and am constantly frustrated by the inability to remove those new wrong words from my dictionary!
10 Ronald Heft on Apr 25, 2007 at 10:26 am:

Glad I could help Crystal.
11 Jeremy on May 1, 2007 at 2:16 pm:

Thank you! That was very helpful
12 Chris Ashley on May 4, 2007 at 2:52 am:

Your instructions worked for Windows 2003 as well.

Thanks for the help.
13 Brad on May 16, 2007 at 10:49 pm:

Thanks a bunch, I was doing a search for a couple of days to try and find a solution for this, I went to correct word which I’d misspelled, I type in rush so at times tend to invert letters like “soemthing” and dang it, I added it
14 Nobody on Jun 2, 2007 at 6:36 pm:

Very helpful, thanks.
15 Aunty Nomus on Jun 4, 2007 at 2:10 am:

THANKYOU!

I’ve been *way* too click happy and have quite an almost useless dictionary. This will help a *lot*. ^_^

What we need now is a plugin to move that evil add button somewhere else, or maybe the Mozilla folks can read this and learn what a pain in the posterior it is now.
16 Will R on Jun 7, 2007 at 10:36 am:

Thanks a million! Awesome! Brilliant! Superb!

I’d added my first wrong word just the other day and had searched through the options within Firefox to try to undo it. Now 5 mins on internet looking how to fix it, or a new easier-to-use dictionary and I find the solution. Great Stuff!

I agree with “Aunty Nomus” we do need a plugin to move that evil add button somewhere else.
17 Bill on Jun 14, 2007 at 8:47 am:

Thanks for the tutorial. FYI: You might need to close & reopen Firefox before you see the custom word in your persdict.dat.
I accidentally added an incorrectly spelled word to my dictionary, immediately googled the fix, & got this page. When I opened my persdict.dat, I didn’t see my word. After I restarted my Firefox, it came up. Hope that helps someone.
18 caleb on Jun 14, 2007 at 4:29 pm:

Thank you for this awesome writeup. I just encountered the same issue.
19 PacketSmasher on Jun 28, 2007 at 2:14 am:

Thanks!!! This whole pointy-clicky thing is overrated
20 David on Jun 30, 2007 at 1:43 am:

I’m in the folder but do not see the persdict.dat . I’ve checked my desktop XP and notebook Vista and the file is not there. Any ideas?
21 Ronald Heft on Jun 30, 2007 at 4:43 am:

David: I’m in the folder but do not see the persdict.dat . I’ve checked my desktop XP and notebook Vista and the file is not there. Any ideas?

Firefox needs to be closed for persdict.dat to be visible. Also, if you didn’t add any custom spellings, the file will not exist.
22 Leslie on Jul 1, 2007 at 4:36 am:

thank you!! very useful
23 Vince on Jul 2, 2007 at 8:10 am:

Many thanks for this, I was pulling teeth trying to find out how to edit the Firefox dictionary as I had a couple of misspelled words in there.

Thanks again
24 SJ on Jul 5, 2007 at 2:40 pm:

The feedback needs to be given to developers about this. The Add to dictionary button should have a confirmation dialog box.
25 s. on Jul 18, 2007 at 9:18 am:

Thanks for this, but I’m stuck…I can’t find my Firefox profile. Part of the problem is obviously that I don’t have an Application Data folder! (I’m using XP.) All I’ve got in there is Cookies, Desktop, Favorites, My Docs, Start Menu, UserData, and WINDOWS. I’ve tried to do a search but keep coming up with nothing.
26 s. on Jul 18, 2007 at 9:26 am:

s.: Thanks for this, but I’m stuck…I can’t find my Firefox profile. Part of the problem is obviously that I don’t have an Application Data folder!

Sorry, never mind. I didn’t realise the App Dat folder was sometimes hidden.
27 Eric Li on Jul 26, 2007 at 7:22 am:

When coming to Application Data, it might be hidden. Do:
Tools -> Folder Options -> Show hidden files and folders -> ok. You may change it back later. Then you’ll see the folder Application Data if it was hidden.

When looking for ‘persdict’, note it doesn’t necessarily needs to show the .dat at the end. If t doesn’t, it’s the same file.
28 Stan on Nov 6, 2007 at 4:36 am:

Thanks for that!
29 McKenna on Nov 14, 2007 at 1:24 pm:

Okay, I’m the dunce here. I am running Windows XP Pro, and I do not seem to have an Application Data folder. I have used explore, I have used search. I have three users: one is [Administrator], one is [All Users], and [User].

So I get as far as Documents and Settings/[User] … and in none of those users do I find a folder called Application Data.

I, too, have a click-happy finger, and I have several common words in my dictionary that are now misspelled, and I would LOVE to remove them.

My apologies for being dense here.
30 Arno on Nov 14, 2007 at 11:21 pm:

Great!
New question: is there a way to edit the standard dictionary? I find all sorts of misspellings that seem to show up as obscure but correct English words. Every now and again I am dumbfounded by the mistakes I make that are not discovered, and they are not my own additons.

Thanks much!!
31 Ronald Heft on Nov 15, 2007 at 1:12 am:

McKenna: Okay, I’m the dunce here. I am running Windows XP Pro, and I do not seem to have an Application Data folder. I have used explore, I have used search. I have three users: one is [Administrator], one is [All Users], and [User].

My apologies for being dense here.

You’re not being dense at all. The Application Data folder is hidden by default so people don’t mess with it by accident. Here’s a good guide for making it visible.

Arno: New question: is there a way to edit the standard dictionary? I find all sorts of misspellings that seem to show up as obscure but correct English words. Every now and again I am dumbfounded by the mistakes I make that are not discovered, and they are not my own additons.

That’s an excellent question. Unfortunately, I don’t have a solid answer for you.

After some quick poking around, I found a en-US.dic file and a en-US.aff file. Both files open in a standard text editor, but are not just a basic list of words. They contain some extra data. You may be alright just deleting the line containing the word you want to remove, but I can’t be certain. Make a backup of both files before proceeding.

On Mac I found the file at:
```
/Firefox.app/Contents/MacOS/dictionaries/
```
I have no clue where those files are located on Windows, but I would assume the Program Files/Mozilla Firefox folder.
32 dibyendu on Nov 18, 2007 at 12:54 pm:

thanks…. nice and very clear…
33 Brian on Dec 2, 2007 at 5:01 pm:

Weird; I just added “occurance” to my dictionary and found this article, looked in the file, and only the words I had purposefully added had made it there o.o

Oh well, I may not have needed it this time around, but it’s good to know for the future!
34 bigfoot13442 on Dec 7, 2007 at 8:00 am:

i don’t have a persdict.dat file in that folder, or anywhere else on my computer. but i do have a dictionary and i did add a word by mistake. what do i do?
35 Ronald Heft on Dec 7, 2007 at 8:43 am:

bigfoot13442: i don’t have a persdict.dat file in that folder, or anywhere else on my computer. but i do have a dictionary and i did add a word by mistake. what do i do?

Are you looking the correct user folder? If so, the file will not exist if no custom words have been added to the dictionary. Are you positive the accidental word actually made it into the dictionary?
36 Sean on Dec 12, 2007 at 9:27 am:

Thanks, appreciated the useful bit of info
37 Tori on Dec 21, 2007 at 9:53 pm:

thank you!!! I had 5 in there and really wanted to fix it… much appreciated!
38 endolith on Dec 31, 2007 at 1:19 am:

Thanks! This should be an add-on.
39 Thomas on Jan 14, 2008 at 1:05 pm:

Thanks – great tip….
40 Hilal Suhaib on Jan 21, 2008 at 12:15 pm:

Thanks a ton for this. Insane how this is the only way to do it eh?? Create a short cut of the DAT file to your desktop for easy access as well.
41 kunar on Jan 28, 2008 at 12:04 am:

thanks a ton. i somehow managed to add 2 words today that didnt belong and couldnt figure this out for the life of me.
42 gt7599a on Feb 14, 2008 at 10:53 pm:

For Windows users I suggest typing the following, it will get around not seeing hidden files/folders, is not specific to the user and is shorter. Environmental variables are your friend.

%appdata%\Mozilla\Firefox\Profiles\
then browse down through the *.default folder, close Firefox and edit away.
43 Thomas Mannino on Mar 5, 2008 at 1:43 pm:

Thank you for this! I love the internet.
44 Daniel on Mar 14, 2008 at 6:58 pm:

Thanks so much. I accidentally added a misspelled word to the dictionary and was able to remove thanks to this post. Very much appreciated! =]
45 Mike Whitla on Apr 10, 2008 at 9:07 pm:

Thanks a ton for this. Got my dictionary all fixed up.
46 Keith on Apr 20, 2008 at 4:28 pm:

Thanks much for this! I too had accidentally added misspelled words to the dictionary and I was able to remove them. We truly need a Firefox plug-in for this!
47 Anthony on Apr 23, 2008 at 12:11 pm:

Thank you – this has helped me several times already.
48 sodapop on May 17, 2008 at 11:21 am:

THANKS!!! I accidentally added two words in two days!!!
49 robin on Jun 9, 2008 at 1:01 pm:

Brilliant stuff. Thanks for this tip.
50 f_w on Jun 9, 2008 at 1:54 pm:

I find it wherry annoying that i have to use Google to find the right spelled word when the firefox speller suggest totally inappropriate alternative words.
Are there any way to add to the suggested word list?
51 Phos.... on Jun 19, 2008 at 12:32 am:

Thanks a lot, mate. Had a bunch of blunders I’ve been wanting to ditch for awhile. The update to Firefox 3.o yesterday seemed like a good time to figure out how.

This page was the top result on a G-Search of edit firefox spelling dictionary, so I’m sure you’re happy about that.

Cheers from Lancaster PA!
52 Andy on Jul 14, 2008 at 10:01 pm:

This tip was a huge help. In addition, you can add words in the text editor that you know should be added like long last names and scientific terms.
53 Stuee on Jul 24, 2008 at 6:37 am:

Thanks for this, now I can correct some of the hundreds of mistakes which come bundled with the British English dictionary as default!

The bloody thing is always trying to tell me how to spell things wrongly, when I know damned well I’m right – but it just puts that modicum of doubt in my mind so I check in a ‘proper’ dictionary, only to be proven correct.

Anyone know who compiles these things? I bet it’s an American (no disrespect, but a lot of the errors seem to be Americanisms).
54 Mary-Lynn on Jul 27, 2008 at 1:52 am:

Thank you for posting this. The only word I had accidentally saved was “because” and it’s the one word I never manage to type right the first time. It finally drove me crazy enough to fix it tonight.
55 Militza on Aug 1, 2008 at 3:09 am:

I’m using a Mac and when I go into the Profiles folder, there is no “xxxxxxxx.default,” only something called “kwbro69x.default.”

I tried showing hidden files, but it didn’t work. Suggestionss??
HELP please!
Thanks!
56 Ronald Heft on Aug 1, 2008 at 8:55 am:

Militza: I’m using a Mac and when I go into the Profiles folder, there is no “xxxxxxxx.default,” only something called “kwbro69x.default.”

I tried showing hidden files, but it didn’t work. Suggestionss??

That folder is the one you want. The Xs are randomized and different for each user.
57 Conner on Aug 12, 2008 at 6:23 am:

Thanks, I accidentally added a misspelled word this morning. This saved me numerous headaches.
Do you happen to know if the file is the same format across platforms? I would like to take my dictionary from ubuntu to my work machine.
58 Shadizilla on Aug 15, 2008 at 11:09 am:

*Thank* you.
Gosh, I was tired of accidentally adding it to the dictionary. Seriously.
This was really simple, too.
59 Pixi on Sep 3, 2008 at 5:14 am:

Thank you so much for this! I found it useful, not only to delete words that accidentally ended up in there, but also for adding in a lot of words I know it wouldn’t have recognised – without having to type them out and clicking to add them in Firefox.

Incidentally, is anyone else amused by the fact that Firefox’s dictionary doesn’t recognise the word Firefox?
60 thomas on Sep 23, 2008 at 3:52 am:

thank you very much…. exceptionally helpful… i was at my wit’s end until i ran across this…. suppose i shouldn’t be so trigger-happy when correcting my spelling…. you’d think that they’d move the “add to dictionary” tab away from the automated spelling corrections….

someone should write to Mozilla… unless, that is, they’ve gotten to large to actually field recommendations from the little guy these days…

any-who… again: thanks!!
61 Nick on Oct 15, 2008 at 2:03 pm:

I found the persdic.dat (which is a funny to say the first 2 times) here:
C:\Users\[ME]\AppData\Roaming\Mozilla\Firefox\Profiles\3bxgj7zp.default

I tried to open it using notepad, wordpad, word processor, microsoft word, openoffice writer, etc. and the only thing that would show up was the word “attatchments” –which is obviously spelled wrong. I even went to a text entry box, typed “hee” added it and checked again..only “attatchments”

so maybe I didn’t exactly catch what you meant by a “standard text editor” or something else is wrong.

thanks for the help man.
-Nick
62 Ronald Heft on Oct 15, 2008 at 5:55 pm:

Nick, that is correct. That file lists words each on a new line that you have added in Firefox. You must have at one point added ‘attatchments’. If you delete that word then save, Firefox will no longer recognize that as spelled correctly.
63 Nick on Oct 15, 2008 at 7:55 pm:

oh yes, and kudos for the speedy responses on here…I realize why that word is in there and i understand the process of deleting the misspelled words and resaving the .dat file.
my question to you was/is why is that the only text in that file? i’ve added hundreds of words, a few misspelled words have slipped by as well…but my question was why is “attatchments” the ONLY word in that file? should I be looking for a clone .dat file or another FF folder somewhere where these words were perhaps saved instead of this .dat file in question?
thanks again ron!
64 Ronald Heft on Oct 16, 2008 at 11:20 am:

Perhaps you’re not in the correct user folder? If you are in the correct one, then I really don’t know. Perhaps Firefox was never saving the added words for you?
65 Sean on Jan 7, 2009 at 10:03 am:

Thank you for the tip. The Mozilla team should really move the “Add to dictionary” context menu item somewhere other than just below the suggested spellings. I’ve accidentally bumped that a couple of times. It’s just horribly bad placement of the menu item.
66 lie on Jan 23, 2009 at 1:17 pm:

I’ve just realized that the reason why I’ve never mistakenly added a wrong word to the Firefox’s dictionary is because, when correcting mistakes, I retyped instead of choosing from the word list (instead of spelling corrector, I used it as misspelling highlighter). Only when I failed to type the correct word a few times, I would choose from the list (i.e. only when I don’t actually know how the word should be spelled).

> Incidentally, is anyone else amused by the fact that
> Firefox’s dictionary doesn’t recognise the word Firefox?

No, it’s because you misspelled Firefox for firefox.
67 Anonymous Pie on Mar 26, 2009 at 12:36 pm:

Awesome sauce! I’m so glad you shared that tip with us. I’ve been trying for ages to correct my custom dictionary. You rock!
68 Chris on Apr 13, 2009 at 11:55 pm:

Thank you!!

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