LSI Keywords
LSI (Latent Semantic Indexing) keywords are terms semantically related to a primary keyword. Including them helps search engines understand the full context of a page's topic, though modern NLP has made strict LSI largely obsolete.
Reviewed by Alexander Yarovenko · Updated: 2026-07-03
What are LSI Keywords?
LSI keywords (Latent Semantic Indexing) are terms and phrases that are semantically related to a primary keyword — words that commonly appear together or that search engines associate with the main topic. The term comes from the LSI mathematical technique, though modern search engines use far more sophisticated NLP (BERT, MUM) rather than pure LSI.
LSI Keywords Examples
| Primary keyword | Related LSI terms |
|---|---|
| Apple (company) | iPhone, Tim Cook, iOS, MacBook, App Store, Silicon Valley |
| SEO | Google, backlinks, keyword research, rankings, organic traffic, SERP |
| Italian restaurant | pasta, pizza, risotto, wine, Naples, reservations, Tripadvisor |
The Reality of LSI in Modern SEO
Strict LSI (the 1988 mathematical technique) is largely obsolete in how Google works today. Google now uses semantic understanding via BERT and MUM to grasp the full meaning of queries and pages. The concept remains useful as a shorthand for "use contextually relevant terms" — but the SEO community often misuses "LSI keywords" to mean any related keyword.
Why Using Related Terms Matters
- Helps Google understand the topic of your page more fully
- Prevents over-reliance on exact-match keyword repetition
- Naturally improves content comprehensiveness (signals topical depth)
- Helps you rank for additional related keywords without creating separate pages
How to Find Related Terms
- Google autocomplete — type your keyword and see suggestions
- Related searches — bottom of Google SERP
- People Also Ask — questions Google associates with your topic
- Clearscope / Surfer SEO — show terms appearing in top-ranking content for your keyword
- Competitor content analysis — what terms do the top-ranking pages use?