Definition

Semantic search

Semantic search retrieves documents by comparing meaning representations rather than matching literal query terms.

It is the retrieval layer underneath most answer engines, and the reason a page can be cited for a phrasing it never contains.

The practical implication for content is to cover a concept thoroughly rather than to repeat a phrase.

Related terms

Embedding Retrieval-augmented generation (RAG)Long-tail query

Nostimates measures semantic search across twelve AI answer surfaces. Request access →

All terms

AEO (Answer Engine Optimisation)GEO (Generative Engine Optimisation)AI Overviews AI Mode Citation share n-sampling Query fan-out Grounding Share of voice (AI)Extraction success rate Surface Answer engine Citation Brand mention Mention rate Confidence interval Statistical significance Citation volatility Non-determinism Reproducibility Identity-free collection Personalisation Locale Residential proxy Bot detection Collection cost Credit Evidence retention Audit trail Parser version Canary prompt Data freshness Cadence Prompt set Head term Long-tail query Competitive set llms.txt robots.txt AI crawler Training crawler Retrieval-augmented generation (RAG)Hallucination Answer box Featured snippet Zero-click search Entity Entity salience Knowledge graph Structured data JSON-LD schema.org FAQ schema Answer-first content Chunk Embedding Prompt injection Market coverage Sentiment analysis Position tracking White-label data