The term Latent Semantic Indexing keywords (LSI keywords) is increasingly common in the context of modern search engine optimization (SEO). While traditional SEO focused primarily on exact match keywords, today’s strategies place greater emphasis on the semantic relationships between terms.

In this article, you’ll learn what LSI keywords are, why they matter for search engine optimization (SEO), and how to use them effectively to boost your organic visibility.

What are LSI keywords?

LSI keywords are terms and phrases that are semantically related to a primary keyword. They are not limited to synonyms; they also include words that frequently appear in the same context or that are topically connected. Google uses advanced algorithms to detect these relationships and determine whether your content aligns with the user’s search intent.

Keywords: then vs. now

In the early days of search engine optimization (SEO), optimization largely revolved around keyword density—the number of times an exact keyword appeared in a text. The more frequently a term was used, the better a page ranked in search results. This often led to unnatural texts overloaded with exact match keywords.

Today, that approach is outdated. Google’s algorithms have become more sophisticated and can now recognize contextual relationships between words. The relevance of a page is increasingly determined by the presence of semantically related terms—known as Latent Semantic Indexing keywords (LSI keywords).

LSI keywords in SEO

LSI keywords help search engines understand the true meaning and topic of a page. A high frequency of a single keyword is now often flagged as spam.

Take, for example, the terms “gym” and “weight loss.” While these are different keywords, Google recognizes that they frequently appear in similar contexts. If you’re optimizing a page for the keyword “weight loss,” incorporating related terms like “workout plan,” “healthy nutrition,” or “fat burning” increases the topical relevance of your content.

By building a broader semantic network around your primary keyword, you signal to search engines that your page offers comprehensive and valuable information—boosting your chances of achieving higher rankings.

How do you identify LSI keywords?

You identify relevant Latent Semantic Indexing (LSI) keywords by finding search terms that are semantically related to your main keyword. You can do this by:

  • Conducting keyword research using tools such as Google Keyword Planner, Ubersuggest, or the Keyword Magic Tool from Semrush. These tools show related terms that are frequently searched alongside your topic.
  • Using Google Suggest: Type your keyword into Google and review the autocomplete suggestions and related searches shown at the bottom of the results page. These are commonly used combinations by real users.
  • Analyzing related terms in existing content: Explore which words and phrases are used by competitors on high-ranking pages covering the same subject.
  • Adding synonyms, subtopics, and contextual terms that logically relate to your main keyword. For example, when writing about “buying your first home,” relevant LSI keywords could include “mortgage,” “property viewing,” and “closing costs.”

By incorporating these terms into your content, you help search engines better understand what your page is about—boosting your chances of ranking higher in the search results.