What are LSI keywords? The short, honest answer
What are LSI keywords supposed to be? In common SEO usage, "LSI keywords" means terms that are semantically related to your main keyword — for an article about "apple" the phone, related terms like "iPhone", "iOS", and "App Store"; for "apple" the fruit, terms like "orchard", "cider", and "pie". The idea is that sprinkling these related words helps Google understand your topic. The problem is the name: LSI keywords, as the industry uses the term, are not a real Google ranking feature.
LSI stands for Latent Semantic Indexing, a document-retrieval technique patented in 1988 — designed for small, static collections of text, long before the modern web existed. Google's own Search Advocate John Mueller has been blunt about it: "there is no such thing as LSI keywords — anyone who's telling you otherwise is mistaken." Google does not run 1980s LSI on the trillions of pages it indexes; it uses far more advanced systems like BERT and MUM to understand language and entities.
So there are really two questions tangled together, and the honest answer splits them apart:
| Question | The "LSI keyword" myth | The semantic reality |
|---|---|---|
| Does Google use LSI? | Yes, it runs LSI on your page | No — Google's Mueller says LSI keywords do not exist |
| What is the tech? | Latent Semantic Indexing (1988) | BERT, MUM, and entity-based understanding |
| What to add | A list of "magic" synonym tokens | Related concepts, entities, and subtopics |
| The risk | Stuffing a word list into the page | Natural depth; no forced density |
| Does the idea help? | The name is wrong… | …but covering a topic fully genuinely ranks better |
In short: the label is wrong, but the instinct behind it is right. Writing about a topic using the related terms and entities a knowledgeable person would naturally use does help — not because of "LSI", but because it is exactly what semantic SEO is built on.
Why the LSI keyword myth won't die
The LSI keyword myth persists because the advice attached to it happens to work, even though the explanation is wrong. Tell someone to "add LSI keywords" and they end up writing more thoroughly about their topic — covering subtopics, using synonyms and related entities — which genuinely improves the page. The good outcome gets credited to a mechanism that does not exist, so the myth survives.
It also survives because it is sellable. A whole category of tools markets "LSI keyword generators", and it is easier to sell a checklist of magic words than to teach the fuzzier skill of covering a topic completely. Most of these tools simply scrape terms that co-occur on the top-ranking pages — which is useful, but has nothing to do with Latent Semantic Indexing.
The danger of the myth is not the word list — it is the mindset. If you treat related terms as a checklist of tokens to sprinkle in, you drift toward keyword stuffing, which hurts you.
Old-school "add your LSI keywords" advice can slide into cramming synonyms into a page at an unnatural rate. That is a keyword density problem, and Google's systems are built to catch it. The fix is to stop thinking about a list of words to insert and start thinking about a topic to cover — which is what the next section is about.
The useful reality: semantically related terms and entities
Here is the part worth keeping. Modern search engines understand a page by the entities and related concepts it discusses, not by matching an exact string. A page about "running a marathon" that never mentions training plans, pace, hydration, tapering, or recovery looks thin to Google's language models, regardless of how many times it repeats "marathon". Covering those related concepts is how you signal genuine depth.
This is the legitimate core that the "LSI" label was clumsily pointing at. When you naturally include the terms, questions, and entities a real expert would use, you do three things Google actually rewards:
- You match more queries. Related terms let one page rank for many long-tail variations, not just the exact keyword. It also clarifies search intent by showing which meaning of an ambiguous word you mean.
- You demonstrate topical completeness. Covering the sub-topics a searcher expects signals that the page fully answers the query — a major factor in modern ranking.
- You feed AI answer engines. Tools like ChatGPT, Perplexity, and Google AI Overviews extract and cite passages that comprehensively address a topic. Rich, entity-dense content is easier for them to trust and quote — the heart of entity SEO.
So the reframe is simple: stop hunting for "LSI keywords" and start asking, "what does someone who fully understands this topic talk about?" That question, not a generator tool, is what produces content that ranks and gets cited.
How to find and use related terms the right way
You find semantically related terms directly from the search results themselves — Google will show you the exact vocabulary it associates with your topic, for free. Skip the "LSI generator" tools and mine these four sources instead:
- People Also Ask. The expandable questions on the SERP reveal the sub-questions searchers expect you to answer. Each one is a subtopic to cover — see what is People Also Ask.
- Autocomplete. Type your keyword into Google and read the dropdown; each suggestion is a real related query pulled from live search data.
- "Searches related to". Scroll to the bottom of the results page for a block of related searches — Google literally listing terms it connects to yours.
- The top-ranking pages themselves. Read the pages already ranking and note the recurring entities, subheadings, and terms they all cover. That overlap is your topic's real vocabulary.
Then use those terms the way a writer would, not a robot. Group them into subtopics, give the important ones their own section or H2, and let the rest appear naturally as you explain the topic in depth. Do not force a term in where it does not belong, and never chase a target count — that is the keyword stuffing trap the myth leads to. Cover the topic completely and the related terms show up on their own.
When the draft is done, verify it instead of guessing. Paste the URL into the free SEO + GEO audit on the homepage — it checks whether your content reads as a complete, topically rich answer, whether your primary keyword sits in the right places, and whether AI crawlers can reach and cite the page. That is a far better signal than any LSI keyword score.