The AI Search & AEO Glossary: Every Term, Defined

Why a glossary for AI search at all?

AI search arrived faster than its vocabulary settled. The acronyms — AEO, GEO, LLMO, AI SEO — are used interchangeably by some writers and as rival schools of thought by others. Definitional content is exactly what large language models reach for when they answer “what is X?”, so a clear, dated, self-contained definition is one of the most reliably cited formats there is. This glossary exists to give you that — and to point you to the deeper guide behind every entry.

One thing sets these definitions apart: every term ties back to a live query–domain index across the three major models — ChatGPT, Gemini and Grok. When we define AI citation footprint, you can go map yours; when we define ghost routes, you can find yours with the free Domain Check. Definitions you can act on beat definitions you can only memorise.

How the terms relate

The glossary clusters into four groups. Read them in this order and the field stops feeling like alphabet soup:

• The disciplines — what you call the work of getting picked by AI: AEO, GEO and LLMO. Largely overlapping labels for the same goal: being the source an answer engine names.
• The units of visibility — what you measure: AI citations, your AI citation footprint, and how to read the index in reverse with reverse AI search on the AI query index.
• The metrics and surfaces — how you score and where it shows: AI share of voice, prompt volume, AI Overviews and the zero-click reality they create.
• The gaps and controls — where you are missing and what you can do: ghost routes and llms.txt (and an honest take on whether the latter does anything yet).

Every term in this glossary

Each entry is a short, self-contained definition with a link to the full guide:

• AEO (Answer Engine Optimization)
• GEO (Generative Engine Optimization)
• LLMO (Large Language Model Optimization)
• AI share of voice
• AI citation
• AI citation footprint
• Reverse AI search
• AI query index
• Ghost routes
• Prompt volume
• AI Overviews
• llms.txt
• Zero-click
• Mention vs citation
• Answer block / atomic answer
• Share of model
• AI Mode (Google)
• GPTBot / ClaudeBot / PerplexityBot
• Google-Extended
• RAG (retrieval-augmented generation)
• AI Overviews vs AI Mode
• Sentiment analysis (AI mentions)
• Citation rate / visibility rate
• Prompt / query bank

Where the glossary points next

The glossary is a hub, not a destination — it funnels you toward the guides that go deep. For the category MentionRadar is built around, start with the Reverse AI Search pillar. For the acronym debate in full, see the AEO, GEO & Fundamentals pillar. And for the fastest possible understanding of any of these terms, run the free Domain Check on a domain you know — the terms make far more sense once you see real citations attached to a real domain.