Definition
Hybrid search
Search that combines keyword matching (such as BM25) with semantic vector search, so results catch both exact terms and meaning.
Vector search finds passages with similar meaning even when the wording differs, but it can miss exact identifiers: case numbers, product codes, legal citations, names. Keyword search (BM25) is excellent at exact terms but misses paraphrases.
Hybrid search runs both and fuses the rankings, for example with reciprocal rank fusion or weighted scores. In most enterprise corpora it is the single most reliable improvement to retrieval quality.
Elasticsearch, OpenSearch, Weaviate, Qdrant and pgvector-based setups can all support hybrid retrieval in different ways.
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