To change the spelling dictionary on macOS, you must add a new language keyboard layout in System Settings. The operating system automatically assigns a specific spell-checker to each input source. By switching your active keyboard layout via the menu bar or keyboard shortcut, you effectively switch the dictionary used for autocorrect and red-underlined text.
Understanding Input Sources and Spell Checkers
macOS does not have a single global spelling dictionary that applies to every application regardless of context. Instead, the spell-checking engine is tied directly to the Input Source currently selected by the user. An Input Source defines both the physical key mapping (how letters are typed) and the linguistic rules applied by the system, including grammar checking, autocorrect, and dictionary suggestions.
If you are typing in English but your system thinks you are typing in French because the French keyboard layout is active, the spell checker will flag valid English words as errors. Conversely, if you want to write in Spanish while using an English keyboard layout, you will need to add the Spanish language input source. This separation allows macOS to support complex multilingual workflows without requiring users to install separate dictionaries for different applications.
For more information on managing peripheral devices and keyboard behaviors, see How to Use Function Key and Standard Key in Extended Apple Keyboard.
Adding a New Language Keyboard
The first step to changing your dictionary is to ensure the language associated with that dictionary is installed as an available Input Source. You do not need to download separate dictionary files; they are bundled with the operating system.
- Open System Settings (or System Preferences on older versions of macOS).
- Navigate to Keyboard in the sidebar.
- Click on Input Sources... located in the main pane.
- Click the + button at the bottom left of the window.
- In the search bar, type the name of the language you wish to use (e.g., "Spanish" or "German").
- Select the language from the list on the left.
- Choose the specific variant if prompted (e.g., "Spanish - Spain" vs "Spanish - Latin America"). Note that some variants may have slightly different default dictionaries.
- Click Add.
Once added, this language appears in your list of available Input Sources. It is now ready to be activated. If you do not see the language option, ensure your macOS version supports that locale. Most major languages are supported natively in modern macOS releases.
Switching Between Dictionaries
After adding the desired language, you can switch between dictionaries instantly. The most efficient method is using the keyboard shortcut. By default, macOS cycles through your Input Sources using Control + Space or Command + Space, depending on your configuration. Some users prefer assigning a dedicated shortcut in System Settings > Keyboard > Keyboard Shortcuts > Input Sources.
Alternatively, you can click the flag icon or language abbreviation in the menu bar at the top right of your screen. A dropdown menu will appear showing all active Input Sources. Click the one corresponding to the dictionary you want to use. Any text you type after the switch will be checked against that language's dictionary.
If you find yourself switching frequently, consider keeping only two Input Sources active to avoid clutter. For example, if you primarily write in English but occasionally draft notes in French, keep both enabled. If you rarely use other languages, remove them from the active list to prevent accidental switches.
See also: Can't Find x86_64 Versions of Applications on MacOS arm64 (M1)
Troubleshooting Persistent Spelling Errors
Sometimes, the spell checker may not update immediately after switching Input Sources. Applications cache their state, so you might need to restart the app to force it to reload the new dictionary rules. If certain words remain underlined in red despite being correct for the selected language, check the following:
- Check the Text Field Settings: In apps like Pages or Microsoft Word, ensure the paragraph language matches the Input Source. Go to Format > Language and select the correct language.
- Disable Auto-Correction Temporarily: Sometimes auto-correction interferes with legitimate terms. You can turn off spell checking entirely for a specific field by holding Option while clicking the "Aa" menu in the toolbar of compatible apps, then selecting Spelling and Grammar.
- Clear Cache: In rare cases, clearing the system’s input cache helps. Restart your Mac to reset all running processes and reinitialize the language modules.
If you are experiencing issues with arrow keys not functioning correctly in terminal emulators after changing layouts, refer to Control + Arrow Keys Not Working in iTerm2 on MacOS.
Managing Custom Words
macOS maintains a shared custom dictionary that learns from your typing habits across all Input Sources. However, some languages allow for more granular control. To add a word to your personal dictionary:
- Right-click (or Control-click) the misspelled word.
- Select Learn Spelling from the context menu.
- The word is now saved to your local dictionary file.
This action adds the word to the user-specific dictionary, which persists across sessions. Note that custom words are generally applied globally within the OS, but some third-party applications may have their own isolated dictionaries. Always verify settings within individual apps if cross-app consistency is required.
Frequently Asked Questions
Does changing the keyboard layout change my actual typing speed?
No, switching Input Sources does not alter the physical mechanics of your keyboard or your typing velocity. It only changes the character output mapping and the linguistic rules applied by the software. Your muscle memory remains intact, but you may need to adjust to different key positions if you switch between QWERTY and AZERTY layouts.
Why is my spell checker still redlining words after I switched languages?
This usually happens because the application has cached the previous language setting. Restarting the application forces it to detect the new Input Source and load the corresponding dictionary. Additionally, check if the document itself has a hardcoded language attribute that overrides the system default.
Can I have multiple spell checkers active simultaneously?
No, macOS only applies one active Input Source at a time. The spell checker mirrors this selection. You cannot run English and French spell checks on the same text block concurrently. You must switch the Input Source to change which dictionary validates your text.
How do I remove a language I no longer use?
Go to System Settings > Keyboard > Input Sources. Select the language you wish to remove and click the - button. This removes the Input Source from your active list but does not delete any data or custom words you have already learned into the system dictionary.
Do third-party apps like Chrome or Firefox follow these settings?
Yes, modern browsers respect the system-level Input Source and dictionary settings. However, some browsers have their own internal spell-checking engines that may offer additional language packs. Ensure that the browser’s internal settings align with your macOS Input Source for consistent results.