Definition

Hallucination

A hallucination is generated content that is factually wrong or unsupported by the cited sources, presented with the same confidence as accurate content.

For brands, the practical risk is misattributed claims: wrong pricing, wrong features, wrong ownership, stated authoritatively in an answer buyers read.

Detecting it requires reading the answer text, not counting citations — another reason evidence retention matters more than a score.

Nostimates measures hallucination 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)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 Semantic search Prompt injection Market coverage Sentiment analysis Position tracking White-label data