What latent semantic indexing describes
Latent semantic indexing is an information-retrieval method associated with analysing patterns of terms across documents. The term is often used loosely in SEO sales language to describe related words, but those are not interchangeable concepts.
A list labelled “LSI keywords” does not establish how Google’s ranking systems work. Do not infer that a website needs to insert a prescribed list of related phrases to receive a particular ranking benefit.
Use related terminology when it helps explain the subject
A useful technical explanation may naturally include connected concepts, examples and distinctions. Choose them because a reader needs them. Repeating terms that do not add information can make the page harder to understand.
For a service page, start with the customer’s question, the real scope and relevant evidence. For a glossary definition, explain the concept accurately and identify the limit of any claim about a search engine.
Avoid a keyword checklist becoming the content
Check whether each section adds something useful and whether the source supports the statement being made. Google’s published ranking-systems guide is a better reference for its described systems than an unsupported claim that a keyword tool exposes an LSI requirement.