Where apps hide your files

Finding Word's Custom Dictionary file

Updated 2026-10-28 · 5 min read

Word for Mac saves every word you add to the spelling dictionary in a single file named Custom Dictionary, inside the shared Office group container. Here is where it is, how to edit it safely and how to carry it to a new Mac.

The location

Word for Mac keeps your custom dictionary in one plain file with no extension:

~/Library/Group Containers/UBF8T346G9.Office/Custom Dictionary

The file is called Custom Dictionary, with a space and no .txt or .dic. On the Mac used for this guide it sits directly in the Office group container, is a few hundred bytes (it holds a short word list) and, when asked what type it is, file reports "Unicode text, UTF-16, little-endian text, with CRLF line terminators". A Microsoft Q&A answer gives the same folder and file name, and an Apple Community thread gives it for Word 2016. Guides written for older Office releases point to other folders, so check which version a tutorial describes.

UBF8T346G9 is Microsoft's team identifier, the same on every Mac. The Library folder is hidden. In Finder, choose Go > Go to Folder (⇧⌘G), paste the folder path (without the file name) and press Return. From Terminal:

open -R ~/Library/Group\ Containers/UBF8T346G9.Office/Custom\ Dictionary

That reveals the file in Finder without opening or changing it.

What is in it

One word per line, nothing else. Every word you choose Add to Dictionary for ends up here. The file sits in the shared Office folder rather than in Word's own container, and Microsoft's dictionary article says a word added to a custom dictionary in one Office program is available for spelling checks in the others. On the Mac used for this guide the file is UTF-16 text, so a tool that assumes UTF-8 will show spaced-out letters or garbage. Opening it in a UTF-8-only editor and saving can corrupt it, which is a reason to prefer Word's own dialog below.

Edit the list from inside Word

This is the safe route, because Word saves the file in the format it expects. Microsoft's Mac steps:

1. In Word, choose Word > Preferences.
2. Under Authoring and Proofing Tools, click Spelling & Grammar.
3. Make sure Suggest from main dictionary only is cleared, then click Dictionaries.
4. Select the dictionary (do not clear its tick box) and click Edit. Word opens the dictionary as a document.
5. Add or delete words, one per line, and save the document.

Microsoft notes that editing a dictionary turns off Check spelling as you type; switch it back on in the same Spelling & Grammar pane afterwards. The Dictionaries dialog also has New and Add for creating or attaching another dictionary. Microsoft's article says Preferences; if your Word menu says Settings, use that.

To add a word you have just been flagged on, Control-click the word with the red underline and choose Add to Dictionary.

Back it up before you touch the file

If you do edit by hand, the order matters: quit Word first, copy the file, then edit.

cp ~/Library/Group\ Containers/UBF8T346G9.Office/Custom\ Dictionary ~/Desktop/Custom\ Dictionary.backup

Then make your change, reopen Word and test a word you added. To restore, quit Word and copy the backup over the live file, which replaces the current list, so do it only when you mean to.

Move your words to a new Mac

Install Office, open Word once so the group container exists, quit Word, then copy your saved Custom Dictionary into the same folder on the new Mac. A Microsoft Q&A thread describes the same replacement as working: back up the default file, drop yours in and make sure the name matches exactly, with the same spelling and no extension. A community tester in that thread also used a Windows CustomRoaming.dic this way by renaming it to Custom Dictionary. That is not an official Microsoft procedure, so keep a backup and test it.

On Windows, Office keeps a separate CustomRoaming.dic file (per the same Q&A thread). Microsoft's Mac documentation does not say whether Word for Mac syncs its list, so keep the file copy as insurance.

When the dictionary does not seem to work

• Word still flags an added word: check that the dictionary is ticked in the Dictionaries list, that Suggest from main dictionary only is cleared, and that the dictionary's language (set in the same dialog) matches the text.
• Add to Dictionary is greyed out or fails: an old Apple discussion links this to the document's language setting. Treat that as anecdotal, and try setting the language for the text first.
• Phantom spaces or odd lines: a third-party guide blames editing the file outside Word. Restore your backup.
• The file is missing: add a word with Add to Dictionary, then look again; Word should create the file. If it still does not appear, check the Dictionaries list for where your dictionary lives.

A custom dictionary is not an exclusion list

Some guides mention an "exclude" list that stops Word accepting certain words. Exclusion dictionaries are documented for Office on Windows; Microsoft's Mac documentation describes no equivalent, so this post does not describe one. If you need a word flagged, correct it in the document or remove it from the list shown in the Dictionaries dialog.

Why a normal search misses it

Finder and Spotlight searches leave out ~/Library, the file has no extension to search on, and the name Custom Dictionary is easy to confuse with the system's own spelling dictionaries. The file also sits in a group container, one of the folders macOS protects.

Finding it again

Type Custom Dictionary into Everywhere and the file appears with its folder, so you can tell it apart from copies you made. Searching for part of a backup name works the same way. The Office group container is protected, so this works once Everywhere has Full Disk Access. It matches file names, not the words inside the dictionary, so use Word's dialog to look for a particular word.

Common questions

Where is the Word custom dictionary on a Mac?

In ~/Library/Group Containers/UBF8T346G9.Office/, in a file named Custom Dictionary with no extension. The Library folder is hidden, so use Go > Go to Folder (⇧⌘G).

How do I edit the custom dictionary in Word for Mac?

Choose Word > Preferences, then Spelling & Grammar under Authoring and Proofing Tools, then Dictionaries. Select the dictionary and click Edit; Word opens it as a document to change and save. Turn Check spelling as you type back on afterwards.

How do I move my Word custom dictionary to a new Mac?

Quit Word on both Macs, then copy the Custom Dictionary file into the same group container folder on the new one. Keep a backup of the file already there first.

What format is the Word for Mac custom dictionary file?

Plain text with one word per line and no file extension. On the Mac used for this guide it was UTF-16 with Windows line endings, so edit it through Word's Dictionaries dialog rather than a UTF-8 editor.