What Is Latent Semantic Indexing?

Adam Steele
Dec 10, 2021

Hand off the toughest tasks in SEO, PPC, and content without compromising quality

Explore Services
Quick navigation

Latent Semantic Indexing (LSI) has long been a source of contention among search marketers. If you Google the term ‘latent semantic indexing,’ you will find both supporters and detractors. There is no apparent consensus on the advantages of using LSI in search engine marketing.

For those hearing the word for the first time, latent semantic indexing (LSI) might be a daunting and perplexing concept.

Fortunately, while it may sound like something that takes a computer science degree, it’s actually a notion you’re probably already acquainted with — especially if you have some basic knowledge of keywords and their tight link with search engine optimization (SEO).

If you’re not aware of the idea, this article will summarize the discussion on LSI so that you may perhaps grasp what it implies for your SEO approach.

Let’s get started, shall we?

What Is Latent Semantic Indexing?

Latent Semantic Indexing, also known as latent semantic analysis, is a mathematical technique that uses singular value decomposition to assist with categorizing and information retrieval on certain key phrases and ideas (SVD). Latent Semantic Indexing (LSI), also known as Latent Semantic Analysis (LSA), is a natural-language processing approach that was created in the 1980s.

Unfortunately, unless you are familiar with mathematical topics such as eigenvalues, vectors, and single value decomposition, the technology itself is difficult to grasp.

Search engines can use SVD to scan unstructured content and discover any links between terms and their context in order to better index these records for online searchers.

Prior to SVD, computers had a tough time distinguishing between synonyms or semantic shifts.

Take the words “silly” and “string” to help paint an image. When these words are separated, they reflect two distinct meanings; but, when they are combined, they produce a completely new concept: “silly string.”

If you work for an e-commerce firm that sells silly string, you don’t want your content to appear for the term “silly” alone — in that situation, you’d need to employ LSI keywords to assist search engines to know which queries your content should appear for in the SERPs.

Because of greater patterns in relevance, the quality of user search has greatly increased as technology has evolved. Computers began to consider the numerous shapes a word may take on a page through “stemming.”

Search engines can give up results based on relevance depending on the content of the site (not using mind-reading, but instead using LSI keywords). In order to deliver better search results, search engines utilize LSI keywords to help add context to sites.

As LSI grew more advanced, the ability to organize thematically emerged, which meant that synonyms became your best buddy for many rank-driven content authors.

Why Is Latent Semantic Index Important?

Natural language processing (NLP) is used in latent semantic indexing to assist a search engine in determining relevant content for a given search term.

Search engines will use LSI keywords to contextualize pages that contain, for instance, the phrase “snake plants” and offer relevant results. Pages regarding snake plants are likely to include LSI keywords such as “sunlight,” “soil,” and “growing conditions,” helping search engines to locate relevant pages based on the user’s search intent as indicated by the search query.

LSI keywords should be incorporated in any SEO strategy for those wanting to boost their digital marketing efforts.

Developing relevant content for your marketing plan is critical for ranking, attracting visitors, and improving conversions. LSI keywords, or semantically similar phrases, can assist enhance the relevance of your website and increase organic search traffic.

LSI, on the other hand, helps to categorize information, making searches more successful and beneficial for everyone from marketer to the publisher to the user. Content created with LSI in mind might result in a better-targeted piece of content that appears (and appeals to!) the correct audience. Simultaneously, LSI-based content allows users to locate content that is relevant to their individual search queries more quickly and simply.

Latent Semantic Indexing FAQ

Does Google use latent semantic indexing?

Some believe that Google employs Latent Semantic Indexing. They think that by saying this, they are implying that Google uses synonyms and semantically similar terms. They’re incorrect. LSI is only one form of semantic language model. It even contains the phrase “semantics.” However, this does not imply that LSI is applicable to all meanings. Bell Labs patented LSI, which is a form of semantics.

On sites, Google’s algorithms are most likely looking for synonyms and semantically similar terms. That is not to say that utilizing some toolmakers’ tools with the initialism LSI in their names can help pages rank higher in search results.

Latent Semantic Indexing, for example, is an old patented technique, but it doesn’t imply Google uses synonyms and semantically related phrases in the same manner that LSI does. Google enjoys synonyms and semantics, but they don’t refer to it as Latent Semantic Indexing.

When an SEO uses such phrases, it might be deceptive and perplexing to clients who seek up Latent Semantic Indexing and find something quite different. There is no information about LSI Keywords in Wikipedia. There is no information on how LSI Keywords may employ LSI. Because LSI Keywords have never been patented, there are no patents that describe how they operate.

In reality, there is little certainty that LSI is a component of Google’s ranking system.

What is an LSI keyword?

LSI keywords are search phrases that are linked to the main keyword you are targeting in terms of SEO (search engine optimization). They help to support your content and add context, making it easier for readers and search engines to comprehend what you’re talking about.

The challenges of synonymy and polysemy are two of the many problems that LSI seeks to tackle.

Using latent semantic indexing (LSI) keywords in your content is crucial to increase its contextuality and provide the following SEO benefits:

  • They improve your website’s search engine ranking: Including LSI keywords in your content helps search engines comprehend your page and improves its ranking strength.
  • Semantic keywords increase the relevancy of your content: Including related words also helps to ensure that you don’t overburden your text with target keywords, a practice known as keyword stuffing.
  • Related terms enhance the number of people who find your content. LSI keywords also assist you in providing a better search and user experience for visitors, which translates into increases in different ranking variables such as time spent on a page, bounce rate, and more.

What are LSI keywords examples?

Some LSI keywords are synonyms, but not all synonyms are LSI keywords. The bulk of LSI keywords are closely similar words and phrases to your primary keyword. So, while utilizing synonyms in your posts might improve your article’s on-page SEO, they are not LSI keywords.

For example, a synonym for the word “coat” is “jacket.” LSI keywords for “jacket” might contain terms such as, winter, warm, reversible, padded, feather down, puffer, and so on.

LSI keywords for “jogging” include “shoes,” “cardio,” and “5k” and so on.

How do I choose LSI keywords?

The first step in locating LSI keywords is to compile a list of critical keywords for your company. After that, coming up with related keywords would be simple. All it takes is a little study to reveal limitless possibilities—and for that, you’ll need tools. Here are five LSI keyword tools to help you identify relevant selections of similar terms:

1. Autocomplete on Google

Google’s quick search function is the most user-friendly approach to locate keywords related to your primary one. All you have to do is put your desired term into Google’s search bar, and you’ll get a variety of suggestions for what you should type next.

Look for the words that are highlighted as suggestions. Make a list of those that are related to your topic and include them in your article.

2. Serpstat 

Serpstat is another useful tool for finding semantically relevant terms for your posts. You will be given a vast selection of words and phrases from which to choose.

Of course, there are several more relevant long-tail keyword finders available, such as Ahrefs and Moz SEO tools. These are useful since they not only give a complete list of relevant target keywords that people commonly search for on the topic, but they also allow you to sort the terms and phrases according to their link strength, search volume, and cost per click.

3. People Also Ask

Yet another incredibly powerful and free resource, the “People Also Ask” box in the search results page will give you a plethora of other possibilities. You may go over some of the results to see if there are any other terms you can use.

4. LSI Graph

LSI Graph is a free LSI Keyword Generator that allows you to rapidly identify all of the phrases that are connected to your core keyword. Simply enter your page’s main keyword and you’ll be presented with a selection of LSI words to pick from.

5. Related Google Searches

You may also enter your primary term into Google and then scroll down to the bottom of the page to locate the section titled “Related Searches.” Examine the terms provided to obtain more ideas for LSI keywords for your article.

Look at the best methods to employ LSI keywords in your content and SEO strategy now that you know how to uncover them utilizing free keyword research tools.

Don’t forget: check out the other definitions (over 200) in our growing SEO glossary.


Hopefully, this article has given you a better understanding of Latent Semantic Indexing.

LSI was first considered to be capable of assisting Google in matching content with relevant queries. However, it appears that the marketing argument about the usage of LSI has yet to find a resolution. Despite this, marketers may take a variety of tactics to guarantee that their work stays strategically relevant.

To begin, synonyms and variations should be included in publications, online content, and sponsored advertising. This explains why people with comparable intentions use language in different ways.

You must continue to write authoritatively and clearly. If you want your content to answer a specific problem, this is an essential requirement. This issue might be a lack of knowledge or a requirement for a certain product or service. When you accomplish this, it demonstrates that you have a thorough understanding of consumer intent.

Finally, you should make extensive use of structured data. Structured data, whether it’s a web page, a recipe, or a FAQ, offers context for Google to understand what it’s crawling.

Keyword research takes time, so let us do it for you.


Hand off the toughest tasks in SEO, PPC, and content without compromising quality

Explore Services

Written by Adam Steele on December 10, 2021

COO and Product Director at Loganix. Recovering SEO, now focused on the understanding how Loganix can make the work-lives of SEO and agency folks more enjoyable, and profitable. Writing from beautiful Vancouver, British Columbia.