Spell check is on by default in Word, but you may need to turn it back on if it was disabled

Microsoft Word checks your spelling as you type. Red squiggly lines appear under words it does not recognize. If you do not see these lines, spell check is either turned off or set to ignore certain documents. You can turn it back on in a few clicks, and you can also adjust what Word flags and how it behaves.

The steps differ slightly between Word on Windows, Word on Mac, and Word online, but the feature itself works the same way in all three. Most people find the default settings work well — Word catches common misspellings and suggests corrections without getting in the way.

Key Takeaways

  • Spell check runs automatically in Word and shows red underlines under words it does not recognize.
  • If you do not see red underlines, go to File > Options > Proofing and check the box next to "Check spelling as you type".
  • You can right-click any red-underlined word to see suggestions or add it to your dictionary if it is spelled correctly.
  • Word lets you ignore certain words, turn off spell check for a single document, or change which language dictionary it uses.

Turn on spell check in Word on Windows

Open Word and go to the File menu in the top left. Click Options at the bottom of the menu. In the Options window, click Proofing on the left side.

Look for the section labeled "Spelling" and find the checkbox next to "Check spelling as you type". If the box is empty, click it to turn spell check on. If the box already has a checkmark, spell check is already enabled. Click OK at the bottom of the window to save and close.

If you still do not see red underlines after turning this on, check the box next to "Hide spelling errors" in the same window — if it is checked, uncheck it. This setting hides the red lines but does not turn off the actual checking.

Turn on spell check in Word on Mac

Open Word and click Word in the menu bar at the very top. Select Preferences from the dropdown. In the Preferences window, click Spelling under the Authoring and Proofing Tools section.

Look for the checkbox next to "Check spelling as you type" and make sure it is checked. You can also check "Use contextual spelling" if you want Word to catch mistakes like using "their" instead of "there". Click the close button (the red circle in the top left corner) to save your changes.

Turn on spell check in Word online

Open your document in Word online (office.com). Click Review in the ribbon at the top. Look for the Spelling button — it looks like a checkmark with an "A" next to it. If the button appears grayed out, click it to turn spell check on.

Word online does not show red underlines the same way the desktop version does. Instead, click the Spelling button whenever you want to check your document. Word will scan the whole document and show you a list of words it flagged, along with suggestions for each one.

What to do when Word underlines a word

When you see a red squiggly line under a word, right-click it (or Control-click on Mac). A menu appears with spelling suggestions at the top. Click any suggestion to replace the word, or click Ignore All if the word is spelled correctly but Word does not recognize it.

If you use a word regularly and want Word to stop flagging it, right-click and select Add to Dictionary. Word will remember this word and never underline it again. This is useful for proper names, technical terms, or brand names that are not in the standard dictionary.

You can also click Ignore to skip just that one instance of the word, or Ignore All to skip every instance in the current document only. The next time you open a document, Word will flag the word again unless you added it to your dictionary.

Change spell check settings for a single document

Sometimes you want spell check on for most documents but off for one — for example, a document full of code or technical jargon. Go to File > Options > Proofing (Windows) or Word > Preferences > Spelling (Mac). Look for the option "Check spelling as you type" and uncheck it, then click OK.

This turns spell check off for all documents. To turn it back on later, follow the same steps and check the box again. If you want to turn spell check off for just one document without affecting others, you can right-click any flagged word and select Ignore All repeatedly, though this is slower than disabling the feature entirely.

Choose which language dictionary Word uses

If you write in more than one language, you can tell Word which dictionary to use. Go to File > Options > Proofing (Windows) or Word > Preferences > Spelling (Mac). Find the section labeled "Writing Style" or "Spelling" and look for a dropdown menu that says "Language" or "Dictionary Language".

Click the dropdown and select the language you want. You can also set different languages for different parts of a document. Highlight the text you want to check in a different language, then go to Review > Language (Windows) or Tools > Language (Mac) and choose the correct language for that section.

Frequently Asked Questions

Why does Word underline words that are spelled correctly?

Word's dictionary does not include every word, especially proper names, technical terms, and newer slang. If a word is correct, right-click it and select Add to Dictionary. Word will stop flagging it in any document you write from that point on.

Can I turn off spell check for just one word?

Yes. Right-click the word and select Ignore All. Word will stop flagging that word in the current document. If you want to ignore it in all documents, add it to your dictionary instead by selecting Add to Dictionary.

What is the difference between spell check and grammar check?

Spell check catches misspelled words. Grammar check catches mistakes like subject-verb disagreement, missing punctuation, and awkward phrasing. Both run automatically in Word, but you control them separately in the Proofing settings.

Does Word check spelling in comments and tracked changes?

Yes. Word checks spelling everywhere in the document, including in comments, tracked changes, and headers and footers. You can ignore flagged words in these areas the same way you ignore them in the main text.

Can I use a custom dictionary in Word?

Yes, but it requires a few extra steps. In File > Options > Proofing (Windows), click Custom Dictionaries, then New to create a new dictionary file. You can then add words to this custom dictionary and Word will use it alongside the standard dictionary.