What about “LSI keywords”?
In SEO, “LSI keywords” is a popular name for related words and synonyms added to a page. The idea that Google uses LSI to rank pages is a myth: Google has said it doesn’t, and the method doesn’t scale to a web of billions of pages.
The advice behind it is still sensible. Search engines use far more advanced language models to understand topics, so a page that naturally covers related terms, subtopics and questions shows that it deals with the subject properly.
What to do instead
- Look at the pages that rank for your keyword and note the subtopics they cover.
- Check “People also ask”, related searches and Google’s autocomplete for questions to answer.
- Write naturally for the reader, using the words they would use.