Query Expansion
Query expansion is a search engine adding related words to what someone typed, such as synonyms or other phrasings, so it can find pages that use different words for the same thing. A standard search textbook describes using a thesaurus, offering suggested searches a person can pick, and learning from how earlier searchers reworded the same query.
Source: Manning, Raghavan and Schütze, Introduction to Information Retrieval (Cambridge University Press, 2008), section 9.2.2, Query expansion, checked October 29, 2026
What Query Expansion means for your business
Google describes a synonym system that does this job. Its example on How Search Works: someone searches "change laptop brightness," the maker's page says "adjust laptop brightness," and Google connects the two. So a page can be found for a question without using every wording of it.
Google says AI Overviews and AI Mode may run several related searches to build one answer. Its example is a question about a lawn full of weeds that also sets off searches about weed killers and keeping weeds out. Our post on query fan-out looks at where those extra searches send the answer.
For your pages, we'd write in the words your customers use and answer the questions they'd ask next. We wouldn't build a separate page for each phrasing. Google says its synonym system can match pages that don't use the searcher's exact words.
If your pages say "HVAC maintenance agreement" and your customers search "furnace tune-up plan," we'd bring the two vocabularies together page by page.
Source: Google, How Search Works: Ranking results, checked October 29, 2026
Last reviewed October 29, 2026. All terms
How AI answers it today
On October 29, 2026, Google's AI Overview cited research papers, vector database and AI developer blogs, Medium and YouTube, and framed the term mostly around AI chat systems. ChatGPT gave a textbook definition with examples and cited nothing.
Our run through ChatGPT and Google's AI Overview, October 29, 2026. A sample, not what every buyer sees.
Related terms in answers and how content gets used
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