LSI Keywords

LSI keywords is a popular SEO term for words and phrases related to a page’s main keyword. The name comes from latent semantic indexing, an older information retrieval technique, but Google has said it does not use LSI, so the label is misleading even though covering related terms is useful.

Written by Paul Hoda, SEO consultant since 2005. Last updated 8 November 2026.

Where the term comes from

Latent semantic indexing is a mathematical method developed in the late 1980s to find relationships between words in a fixed collection of documents. It helped early retrieval systems understand that documents about “cars” and “automobiles” might be relevant to the same query. It was designed for small, static document sets, not a web of billions of constantly changing pages.

Over time, SEO tools and blogs began calling any related term an “LSI keyword”. For a page about coffee, that might mean “espresso”, “arabica”, “grind size” or “brewing”. The idea is sound; the name is not. Many tools that list “LSI keywords” are really showing words that frequently appear on top-ranking pages, or simple autocomplete suggestions, rather than anything produced by latent semantic indexing.

What Google has said

Google representatives have stated publicly that there is no such thing as LSI keywords in Google’s systems. Search has moved far beyond 1980s methods. Google uses language models such as BERT and other machine learning systems to understand meaning, context and the relationships between concepts.

These systems can recognise that a query and a page are about the same thing even when they share few exact words. This broader field is known as semantic search.

Why related terms still matter

Although LSI itself is a myth in modern SEO, the underlying advice has value. Pages that naturally cover a topic in depth tend to use the vocabulary an expert would use. That helps:

  • Search engines connect the page to a wider range of relevant queries, including long-tail variations.
  • Readers find the details they expected, rather than a thin page repeating one phrase.
  • Your site build topical authority across a subject.

Better ways to find related terms

  1. Look at the People Also Ask box and related searches for your keyword.
  2. Review top-ranking pages and note the subtopics they all cover.
  3. Use keyword research tools to find questions and variations.
  4. Identify the people, places, products and concepts linked to the topic, known as entities.
  5. Ask customers or sales teams what words they use when describing the problem.

Common mistakes

  • Pasting a list of “LSI keywords” from a tool into copy without regard for meaning or flow.
  • Treating related terms as a checklist instead of a sign of real topic coverage.
  • Paying for tools or services that promise rankings from “LSI optimisation”.
  • Swapping the main keyword for synonyms so often that the page’s focus becomes unclear.

The more useful frame is semantic SEO: writing pages that thoroughly cover a topic and its connected ideas.

Key Takeaways

  • LSI stands for latent semantic indexing, a 1980s retrieval method.
  • Google has said it does not use LSI keywords.
  • Covering related terms and subtopics is still good practice.
  • Find related terms from searches, competitors and customer language.
  • Write for topic depth, not from a list of terms.

Related Terms

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