Semantic Search
Finding documents by meaning, not by keyword overlap, using embedding similarity.
Last updated: April 26, 2026
Definition
Semantic search uses embeddings to find documents that mean the same thing as the query, even when they share no words. "Cancel my order" matches a document titled "Refund process for returns." Pure semantic search has a known weakness: it misses exact-match queries (product SKUs, error codes). The fix is hybrid search. Combine semantic similarity with traditional keyword (BM25) scoring. Most production RAG systems use hybrid search; pure semantic loses on the long tail.
When To Use
For any user-facing search where natural-language queries dominate. Add BM25 if exact match queries matter (most B2B applications).
Related Terms
Building with Semantic Search?
I've shipped this pattern in real production systems. If you want a second pair of eyes on your architecture, that's what I do.