What is Query expansion?
Verified 5 August 2026
The classic fix for vocabulary mismatch in lexical search: add synonyms, expand abbreviations, include morphological variants. It reliably improves recall and reliably damages precision, because expansion terms are not always relevant.
Semantic retrieval makes most query expansion unnecessary — the embedding already places synonyms near each other. It remains useful for abbreviations and domain jargon that the embedder was not trained on.
Common questions
What is Query expansion?
Query expansion adds related terms to a query to improve recall when the user’s vocabulary differs from the documents’.
How does Query expansion work in practice?
Semantic retrieval makes most query expansion unnecessary — the embedding already places synonyms near each other. It remains useful for abbreviations and domain jargon that the embedder was not trained on.
See it working
The free tier is 10,000 requests a month with no card — enough to test any of this against your own queries.