lsi keywords
Also called: Latent semantic indexing (LSI), LSI, latent semantic indexing keywords, Latent semantic indexing, semantically related keywords
LSI keywords is a popular SEO term for words and phrases topically related to your main keyword. The name is a misnomer: real latent semantic indexing is a document-retrieval method patented in 1988 and published in 1990, and Google has said it does not use "LSI keywords" as a ranking factor.
Why the name is wrong
Latent semantic indexing is a real technique from a 1990 paper by Deerwester and colleagues. It runs singular value decomposition on a large term-by-document matrix to surface hidden relationships between words, which helps a retrieval system handle synonyms and words with more than one meaning. It was patented in 1988 and built for small, static collections, not for hundreds of billions of web pages.
That history matters because “LSI keywords” implies Google keeps a secret list of related words you must sprinkle in. It does not. John Mueller has said plainly that “we have no concept of LSI keywords,” and there is no evidence Google ever used LSI to rank pages. Modern relevance comes from systems like BERT, not a 1980s matrix method.
What people call LSI keywords are just topically related terms. For a page on espresso machine, that includes portafilter, tamper, boiler, bar pressure, and descaling. These do not help because a tool flagged them in a list. They help because covering them signals you actually wrote about the subject in depth. Write for the topic and the related vocabulary shows up on its own.
How it affects your traffic
Chasing "LSI keyword" lists from tools wastes effort and can bloat a page with forced synonyms that read badly and convert worse. The traffic win comes from mapping the full topic (subtopics, entities, and the questions real searchers ask) so one page can rank for a whole cluster instead of a single phrase. That is a content-strategy call, not a find-and-replace task. Our SEO Consulting work builds that topic map and the internal linking around it, so you stop padding pages with related words and start covering intent.
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