Correct Words Underlined in Word? Check the Passage’s Proofing Language
By ON Lab · Sources checked November 6, 2026
If many correctly spelled words in Word are underlined, first select an affected passage and inspect Review → Language → Set Proofing Language. Check the language and regional dictionary for that text. Changing the application's menu language or turning spelling checks off does not establish that the passage is being checked correctly.
Inspect the text setting before assuming a cause
A recent Windows Word reader reported red underlines under most words in otherwise correctly spelled paragraphs. A wrong proofing language is one condition worth checking, but the report alone does not prove the cause in a private document.
Work on a copy if the document is important. Select a representative affected paragraph first instead of changing every language setting across Office. In a multilingual document, applying one language to everything can make one section look better while making another section wrong.
1. Check the selected passage's dictionary
- Select a word or paragraph that is being checked incorrectly.
- Open Review → Language → Set Proofing Language.
- Read the language assigned to the selection.
- Choose the language actually used in that passage, including the intended regional variant where relevant.
- Keep Do not check spelling or grammar clear if the passage should be checked.
- Confirm and inspect the same text again.
English (United States) and English (United Kingdom), for example, are not identical spelling dictionaries. A regional spelling difference should be investigated as such rather than fixed by adding every underlined word to a custom dictionary.
Word's display language controls the application's interface. The proofing language used for selected text is a different setting. An English ribbon does not prove that the selected paragraph is being checked with the intended English dictionary.
2. Apply the right scope
If the small affected passage improves after choosing the correct language, apply that same correction to the other text that actually uses that language. In a single-language document, selecting the intended whole body can be appropriate. In a mixed-language document, work with the relevant passages rather than imposing one language on all of them.
Recheck text in distinct areas such as a text box or header when those areas are affected. Do not assume a selection in the main body establishes every separate text area's proofing state.
Keep the original wording intact while changing the proofing setting. Accepting a spelling suggestion changes the text; assigning a dictionary changes how the existing text is assessed. Verify which operation you are performing.
3. Understand automatic detection and available tools
Microsoft documents automatic language detection for multilingual writing, while also noting that short mixed-language passages may not be recognized correctly. For an ambiguous passage, explicitly selecting its language can be more useful than repeatedly toggling detection.
Microsoft says automatic detection is not necessary when using only one language. Choose the setting that fits the document instead of treating “always on” or “always off” as a universal fix.
Check that proofing tools are available for the intended language. Microsoft's language preferences identify proofing availability and installed tools. On a managed computer, consult the administrator if the required tools are missing. Do not change account-wide authoring preferences or Windows keyboard languages merely to clear one paragraph's underlines without understanding that broader scope.
4. Verify that checking still works
The disappearance of every red underline is not sufficient if spelling checks were simply disabled. Confirm that Do not check spelling or grammar is clear for the intended text, then use a disposable copy to check a known misspelling. Observe whether Word flags or corrects it rather than certifying success from a clean-looking paragraph alone.
Read the original words again. A product name or specialist term can be absent from a dictionary without making every suggestion correct. Review such terms individually; do not use Add to Dictionary on an entire document's unexpected markings.
Save the working document, close it and reopen it. Select the same passage and recheck its language and the observed proofing behavior. This separates a retained text setting from an apparent temporary improvement.
If the correct language is already selected
Do not keep switching the passage between unrelated languages. Check Microsoft's proofing troubleshooting for enabled language tools, checking exclusions and custom dictionary issues. Compare a small new non-sensitive document if that helps establish whether the issue is confined to one file.
If new text repeatedly changes its proofing language, note the input language and how the text was inserted. Microsoft's guidance explains a relationship with Windows keyboard language, but that does not prove the reader's particular cause. Record the exact settings before making broader changes.
When asking for support, include the Word version, operating system, selected passage language, intended dictionary and whether a small test document behaves differently. Avoid posting a private document publicly just to show the underlines.
Keep the completion check precise
Success means that the intended text is assigned the appropriate available dictionary and checking behaves as expected after saving and reopening. It is not a guarantee that every grammar or writing-style suggestion is correct, or that every Editor feature exists in the account's language and edition. This source-based guide does not reproduce the reader's Windows installation or establish a universal product defect.