What Is Latent Semantic Indexing (LSI)?

LSI stands for latent semantic indexing, which is the method that Google and other search engines use to study and compare relationships between different terms and concepts. These keywords can be used to improve SEO traffic and create more visibility and higher rankings in search results.

SOURCE: https://www.dotcominfoway.com/blog/how-to-use-LSI-keywords-to-boost-seo-traffic/

A free website to get LSI data is Semantic Link.