LibreOffice is an excellent and free alternative to Microsoft Office and especially Microsoft Word, in particular. However, one will notice that the annoying Autocomplete function is turned on by default and prevents the application from being usable if you are typing while not paying close attention to the screen (such as typing a handwritten document or from notes or during a meeting). Essentially, it completes words longer than 8 characters by default, and hitting “Enter” also selects that suggested word. It remembers every word longer than 8 characters and litters your documents with them.
Here’s how to turn that off! Go to Tools > Autocomplete, then choose the Word Completion tab on the right. The box will be checked for “Enable Word Completion”… Uncheck it! You may also adjust other settings to prevent automated mistakes in the future, and you can individually delete each word from its list before hitting OK to save your changes and keep Autocomplete from ruining your documents.
https://www.howtogeek.com/341769/how-to-use-customize-or-disable-autocomplete-in-libreoffice-writer/