Search engines no longer rely on exact keyword matches. One common question that still comes up is:

What are LSI keywords (Latent Semantic Indexing keywords), and do they help with rankings in 2025?LSI keywords don’t exist in Google’s algorithm they’re an outdated concept from the 1980s. What matters in 2025 is semantic SEO, which focuses on meaning, context, and user intent.

If you’ve ever searched “Define LSI keywords” or “Explain LSI keywords,” you’re not alone this guide clears up what the term means, why it’s outdated, and what to do instead.

LSI keywords come from Latent Semantic Indexing, a system created in the 1980s for analyzing patterns in large sets of text. The term still circulates in SEO spaces, but Google has confirmed it doesn’t use LSI as part of its ranking algorithm. It’s a legacy concept with no real value in modern search.

Modern SEO no longer rewards keyword repetition it values clarity, meaning, and contextual depth

As generative engines like ChatGPT, Gemini, and Perplexity reshape how information is surfaced, understanding how your content is interpreted across these systems is becoming just as critical as traditional rankings.

To see how visibility tracking works across search and AI platforms.

Semantic SEO is what actually matters today. It focuses on meaning, context, and how AI visibility platforms and search engines interpret the relationships between words and topics. The goal is to match intent, not repeat phrases.

According to SE Ranking’s 2025 report The average monthly share of organic traffic is 58%, showing a steady 2.39% rise from January through December 2024.

This guide walks you through the outdated myths to ignore, proven tactics that work today, and how to align content with what search engines actually understand in 2025.


What Are LSI Keywords and Why They Don’t Exist

Many SEO blogs still mention “LSI keywords” as if they’re a legitimate part of Google’s algorithm. This leads to outdated strategies and misinformed content decisions. Before applying any keyword technique, it’s important to understand where the term came from and why it’s no longer relevant.

If you’re trying to explain LSI terms or define LSI in the context of search engines, start here: LSI stands for Latent Semantic Indexing. Below we break down where it came from—and why Google never used it for rankings.

What is Latent Semantic Indexing (LSI)?

Latent Semantic Indexing was a mathematical system created in 1988 to find patterns in large sets of text. It was designed to improve document retrieval in early databases—not for search engines.

LSI worked by identifying patterns in how terms co-occurred and mapping them into topics using singular value decomposition (SVD). The goal was to reduce noise in large documents and uncover hidden structures in word use.

Visual diagram explaining Latent Semantic Indexing process

Some SEO communities still reference LSI as if it were a ranking signal. This creates confusion, especially for beginners, because it sounds technical and plausible. But using “LSI keywords” today can distract from building content that actually matches user intent.

Why Google Doesn’t Use LSI

Modern SEO practices focus on user intent, contextual understanding, and topical authority—none of which require outdated indexing systems like LSI. It was never designed to scale to billions of documents, nor can it process modern language nuances.

In 2019, Google’s John Mueller addressed the confusion

“There’s no such thing as LSI keywords – anyone who’s telling you otherwise is mistaken, sorry.” (Source: Search Engine Roundtable)

Many marketers still ask, “How do LSI keywords improve SEO?” or “Can LSI keywords impact results?” The short answer: they don’t as a signal—any uplift people saw was simply clearer topical coverage, not “LSI” itself.

Google now uses advanced systems like BERT, Neural Matching, and MUM that analyze intent, sentence structure, and contextual meaning—not simple word pairs.

LSI ≠ Synonyms ≠ Semantic Terms

  • LSI keywords: Based on outdated indexing methods from the 1980s. Not used by Google.
  • Synonyms: Words with similar meanings that can often be used interchangeably.
    Example: “Search engine optimization” and “organic search strategy.”
  • Semantically related terms: Words or entities contextually linked by topic or user intent, not necessarily synonyms.
    Example: For “What are LSI keywords?”, semantically related terms might include “semantic SEO,” “Google ranking factors,” “BERT algorithm,” and “search intent.”
How to integrate LSI keywords into content? Treat any “LSI list” as semantic prompts. Use the terms naturally to expand coverage—don’t force them as ranking tricks.

Why Are LSI Keywords Important For SEO?

LSI keywords are important for SEO because they help provide context, relevance, and depth to your content, allowing search engines to better understand what your page is about. The term “LSI keywords” refers to words and phrases that are semantically related to a primary keyword, enriching the meaning and clarity of your content.

However, it’s important to note that while the concept of Latent Semantic Indexing (LSI) was developed in the 1980s to analyze relationships between words in smaller datasets, Google does not use LSI technology in its search algorithms. In fact, in 2019, Google’s John Mueller clarified, “There’s no such thing as LSI keywords – anyone who’s telling you otherwise is mistaken, sorry.

Despite this, using semantically related terms within your content remains beneficial for SEO. Incorporating related phrases naturally improves content comprehensiveness, helping search engines understand context and user intent more effectively.

This aligns with modern SEO practices, where search algorithms prioritize high-quality, contextually relevant content over simple keyword repetition.

In summary, even though “LSI keywords” as a concept is outdated and not directly used by Google, the practice of adding semantically related terms continues to play a vital role in improving content relevance, enhancing user experience, and potentially boosting search engine rankings.