The GEO Glossary defines the vocabulary of the answer-engine era — the architecture, mechanics, and disciplines underneath how AI systems now answer questions about brands, people, products, and ideas. Entries are working definitions, refined through original reporting at Everything-PR. Where one entry references a concept defined elsewhere, the term is linked. Where an entry has a long-form essay, the essay is linked at the foot.
A
Answer-Engine. A search counterpart that returns a synthesized answer rather than a ranked list. ChatGPT, Claude, Perplexity, Gemini, and Google AI Overviews are the major examples. The defining architecture of the era that began around 2023, when these systems crossed mainstream adoption. See From Search to Answer and The Answer-Engine Era.
AI Visibility. The degree to which a brand is present, accurate, and on-strategy inside AI-generated answers. The goal of GEO. See AI Visibility.
C
Citation. Being named, quoted, or referenced inside an AI-generated answer. A new unit of internet authority that operates alongside the hyperlink. See From Link to Citation.
Citation Share. The percentage of AI-generated answers in a defined category that cite a given brand. A standing performance metric for the era. See Citation Share.
Credentialed Truth. The source layer AI engines tend to reach for when the cost of being wrong is high. Peer-reviewed research, government agencies, professional associations, named credentialed practitioners. The character of the Expert Layer. See Expert Sources and the Credentialed Truth Layer of AI.
E
Encyclopedia Question. A prompt with a settled, verifiable answer that does not depend on the asker's situation. AI engines tend to ground these prompts on convergent authoritative sources. Contrasts with judgment question. Most real-world prompts are hybrids of the two. See Encyclopedia Questions vs Judgment Questions.
Expert Layer. The credentialed-truth source layer underneath AI answers. Anchored in peer-reviewed publications, government and regulatory bodies, accredited professional associations, and named credentialed practitioners. The layer that tends to carry most weight on high-stakes prompts. See Expert Sources and the Credentialed Truth Layer of AI.
G
GEO (Generative Engine Optimization). The discipline of earning inclusion inside AI-generated answers. Emerged as the answer-engine-era counterpart to SEO. See What GEO Is.
Grounding. The process by which AI-generated language gets anchored to verifiable, externally validated sources. Different question types tend to activate different grounding behaviors. See The Grounding Stack.
Grounding Stack. The five-layer source architecture underneath AI answers — Reddit (judgment), Wikipedia (identity), tier-1 news (recency), expert sources (credentialed truth), owned properties (self-description). The canonical EPR framework for source-layer architecture. See The Grounding Stack.
I
Identity Layer. The structural-definition source layer underneath AI answers, anchored primarily in Wikipedia. The layer AI engines tend to consult first when asked who or what something is. See Wikipedia and the Identity Layer of AI.
J
Judgment Layer. The community-consensus source layer underneath AI answers, anchored primarily in Reddit. The layer AI engines tend to lean on for verdicts, comparisons, and lived-experience prompts. See Reddit and the Judgment Layer of AI.
Judgment Question. A prompt with a contingent answer that depends on values, context, and lived experience. Contrasts with encyclopedia question. The class of prompt where messy truth dominates. See Encyclopedia Questions vs Judgment Questions.
M
Messy Truth. The conversational, contested, partially contradictory ground state of human opinion. The source material AI engines tend to prefer for judgment questions because it provides distributional grounding rather than single confident assertions. See Messy Truth.
N
News Layer. The recency-and-credibility source layer underneath AI answers about the present. Anchored in tier-1 publications — Reuters, Bloomberg, the Financial Times, the Wall Street Journal, the Associated Press, the New York Times, and their equivalents. Coverage tends to depreciate, with the past quarter weighted heavier than older coverage on time-sensitive prompts. See Tier-1 News and the Recency Layer of AI.
Notability Threshold. Wikipedia's standard for entry creation — significant coverage in reliable independent sources. The entry point to the Identity Layer. Cannot be manufactured. See Wikipedia and the Identity Layer of AI.
O
Owned Layer. The self-description source layer underneath AI answers — the brand's own documentation, pricing pages, help content, primary-source identity. The only layer the brand fully controls. The layer that tends to be weighted least for evaluative claims. See Owned Properties and the Self-Description Layer of AI.
R
Retrieval Anchor. A piece of content AI engines reach for when grounding an answer. The unit of source material inside GEO. See The Retrieval Anchor.
S
Source Ecosystem. The full connected universe of sources AI engines retrieve from when generating answers, spanning the five source layers of the Grounding Stack. The thing brands build presence inside through GEO. Sometimes referred to as the underlying source base or retrieval substrate.
T
Tier-1 Publications. The small set of news outlets AI engines tend to weight disproportionately inside the News Layer — Reuters, Bloomberg, the Financial Times, the Wall Street Journal, the Associated Press, the New York Times, and a handful of comparable peers. See Tier-1 News and the Recency Layer of AI.
Trust Discount. The structural devaluation AI engines tend to apply to evaluative claims a brand makes about itself. Owned-content claims that the brand is "leading" or "best" tend to carry less weight than the same claim made by a third party. See Owned Properties and the Self-Description Layer of AI.
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Further reading on Everything-PR:
The Grounding Stack series · What GEO Is · The Retrieval Anchor · Citation Share · AI Visibility · AI Intelligence
Everything-PR covers communications, reputation, AI visibility, public affairs, media systems, and digital discovery in the answer-engine era. Publishing since 2009. Thirty verticals. Original reporting, research, and analysis. Every page reported, sourced, and built to be cited.
