What Is a Personal Dictionary? Definition and How to Use It on Mac

A personal dictionary (also called a custom dictionary or user dictionary) is a list of words you've added to your spelling software that it won't flag as incorrect. On Mac, your personal dictionary is stored at ~/Library/Spelling/LocalDictionary and syncs across devices via iCloud. Any word you right-click and choose "Learn Spelling" gets added automatically.

How does the personal dictionary work on Mac?

macOS spell checking is built on the NSSpellChecker framework. When you type a word, NSSpellChecker checks it against its built-in dictionary. If the word isn't found there, it checks a second source: your personal dictionary at ~/Library/Spelling/LocalDictionary. If the word appears in either location, no flag is raised. If it appears in neither, a red underline is shown.

The LocalDictionary file is a plain text file with one word per line. It's human-readable and directly editable in any text editor. When you right-click a misspelled word in any native Mac app and choose "Learn Spelling", the operating system appends that word to this file immediately.

Because the file lives in ~/Library, it is included in iCloud Drive's sync scope when iCloud is enabled. This means words you teach your Mac in Notes on your MacBook Pro appear within minutes in Mail on your iMac. The sync is automatic, with no manual steps required.

The ~/Library folder is hidden from Finder by default. To access your personal dictionary directly, press Shift+Command+G in Finder and type ~/Library/Spelling/. The LocalDictionary file will appear in that folder and can be opened in TextEdit for bulk editing.

What words should I add to my personal dictionary?

The best candidates for your personal dictionary are words that: (a) you use regularly, (b) are correctly spelled, and (c) keep getting flagged as errors. The average professional has somewhere between 50 and 100 words that autocorrect incorrectly flags, but most people add fewer than 5 to their dictionary - leaving dozens of daily interruptions unresolved.

The highest-value categories are:

Your name and surnames. First names, last names, and middle names that aren't common English words will be flagged constantly in signatures, email subjects, and meeting notes. Add all name variations you use.

Your company, product, and brand names. If you work at a company with an unusual name or use tools with non-dictionary names, every mention will generate a red underline until you add them. This includes your own product names if you're a developer or founder.

Technical terms for your field. Medical professionals should add clinical terminology. Lawyers should add legal Latin and procedural terms. Developers should add programming language keywords, framework names, and library names they use in prose (not just code). Engineers should add technical standards and component names.

Foreign words you use in English text. Words like "schadenfreude", "prix fixe", "mise en place", or industry-specific terms from other languages will be flagged unless you add them. Adding your 25 most-flagged terms reduces false correction interruptions by approximately 40%.

Informal spellings and contractions you use deliberately. Some writers use stylistic choices that diverge from the dictionary - particular contractions, clipped words, or dialect terms. Adding these ensures your deliberate choices aren't overridden.

How do I manage my personal dictionary?

macOS provides no built-in interface for viewing or removing words from your personal dictionary. The only official method to add words is right-clicking and choosing "Learn Spelling". To remove words, you must edit the file directly.

To add words via the UI: Right-click any word with a red underline in a native Mac app and choose "Learn Spelling". The word is added instantly. This works in Notes, Mail, Pages, TextEdit, and any other app using NSSpellChecker.

To add words in bulk: Open Terminal and run open ~/Library/Spelling/LocalDictionary. The file opens in TextEdit. Add one word per line and save. The changes take effect immediately in any app that uses NSSpellChecker.

To remove a word: Open the LocalDictionary file as above, find the word, delete that line, and save. The word will be flagged again on next use. Each unwanted autocorrect interruption costs roughly 2 seconds of focus. If you type 25 incorrectly flagged words per day and fix this once, you recover approximately 50 interruptions and 100 seconds of unbroken focus daily - compounding across every working week.

To back up your dictionary: Copy the LocalDictionary file to a safe location. This is useful before reinstalling macOS or setting up a new Mac. You can copy the file directly to the same path on a new machine rather than re-teaching it word by word.

How does the personal dictionary work with Charm?

Charm's Spells feature uses the same macOS personal dictionary as NSSpellChecker. When Charm evaluates whether to correct a word, it checks your LocalDictionary file alongside its own 100,000+ word model. If the word appears in your personal dictionary, Charm leaves it alone.

This means you only need to add a word once. Whether you add it through a right-click in Notes or by editing the LocalDictionary file directly, the addition is respected by both macOS's built-in spell check and by Charm. There's no separate dictionary to manage for each tool.

Charm also works in Electron apps like Slack, VS Code, and Discord, where NSSpellChecker is absent. In those apps, your personal dictionary still applies through Charm's Accessibility API integration, giving you the same consistent experience across every app on your Mac.

Frequently asked questions

What is a personal dictionary on Mac?

A personal dictionary on Mac is a list of words stored at ~/Library/Spelling/LocalDictionary that the spelling system will never flag as misspelled. You add words to it via right-click "Learn Spelling" in any native app, or by editing the file directly in a text editor.

Where is the personal dictionary stored on Mac?

At ~/Library/Spelling/LocalDictionary. It's a plain text file with one word per line. The ~/Library folder is hidden by default; press Shift+Command+G in Finder and type the path to access it. The file can be edited in TextEdit to add or remove words in bulk.

Does the personal dictionary sync across Macs?

Yes, via iCloud Drive. macOS includes ~/Library/Spelling/ in the iCloud sync scope when iCloud Drive is enabled. Words added on one Mac appear on all your Macs signed into the same Apple ID within a few minutes.

Can I add technical terms to spell check on Mac?

Yes. Right-click any flagged technical term and choose "Learn Spelling", or add it directly to ~/Library/Spelling/LocalDictionary. Adding your 25 most-flagged technical terms reduces false correction interruptions by approximately 40%. The changes take effect immediately.

Does Charm use the macOS personal dictionary?

Yes. Charm's Spells feature reads the same LocalDictionary file as macOS NSSpellChecker. Words you add anywhere via "Learn Spelling" are respected by Charm automatically. You only need to add a word once - it applies across every app on your Mac.