The green wavy line in Microsoft Word is used when Word think you make a grammatical mistake. (The red one is used when you make a spelling mistake)
There should be an option in the Word, "Check grammar as you type". You can turn it off/on.
Adding some Microsoft links with more information.
In Microsoft Word, a green wavy line indicates a potential grammatical error, such as a sentence fragment or a punctuation issue. It is a signal for you to review and possibly correct the highlighted text to improve the overall clarity and correctness of your writing.
Word also has a grammar checker that displays a green wavy line below a phrase or sentence when a POSSIBLE grammatical error is detected. Right click the green wavy line to display suggested corrections.
Wavy Red line
It means it (most likely/probably) is a grammar mistake. However, I do think that Microsoft Word (any version) has and can make mistakes with grammar and/or spelling.
In Microsoft Word, wavy lines can indicate various types of issues. For example, a red wavy line typically signifies a spelling error, while a blue wavy line indicates a grammatical mistake or style suggestion. Additionally, when using the SmartArt feature or drawing tools, you can create custom wavy lines for design purposes. These visual elements enhance both the functionality and aesthetics of documents.
Green wavy underline indicates grammar "mistakes" (you have to turn the grammar correction function on to have Word indicate it has found mistakes)
When a word is underlined by a red wavy line, it signifies that that word is misspelled.
A red wavy line indicates a possible misspelled word.The green wavy line indicates grammar errors or sentence format errors.
Green wavy line
microsoft word
The green wavy line under a word or phrase in a document typically indicates a grammar or style suggestion. This feature is often part of word processing software, alerting users to potential grammatical errors or areas where clarity and conciseness could be improved. It serves as a helpful tool for enhancing the overall quality of writing.
A blue wavy line in Microsoft Word typically indicates a potential grammatical error or a stylistic suggestion. This feature is part of the program's grammar checking tool, which helps users improve their writing by highlighting issues such as sentence structure or word choice. Users can right-click on the underlined text to see suggestions for corrections or adjustments.