How to Write a Definition Section That AI Models Quote Verbatim

Why definitions are the highest-leverage citation surface

When a reader asks an AI model "what is X", the model is choosing between paraphrasing from many sources or quoting one source directly. Quoting is the safer move because it transfers the credibility judgment to the source. The source that gets quoted is usually the one that wrote the cleanest, most extractable definition.

That makes a well-written definition the single highest-leverage citation surface on a page. A page with a great definition earns citations on every "what is X" query for the term, and the citation usually surfaces the brand name in the citation context.

The four-element definition pattern

The pattern below is what OnlyAEO observes consistently across AI-cited definitions.

1. The term, in bold or as a heading. The first signal is structural: the term has to be visually identifiable as the subject of the definition.

2. A one-sentence functional definition. The sentence answers "what is this" in the simplest direct form. No hedges, no caveats. Specific functional language.

3. A two-sentence elaboration. Two sentences that add context, scope, or boundaries. This is where most definitions improve by being specific.

4. A named source or methodology in the elaboration. "Citation rate, as measured by OnlyAEO's standard methodology, is the percentage of conversations across five AI models in which the brand is named." The named entity gets surfaced when the definition is cited.

The four elements together produce verbatim-quote citations. Any one missing usually produces a paraphrase or no citation at all.

A working example

The example below is the OnlyAEO definition of "citation rate" as it appears in the glossary on onlyaeo.com.

Citation rate. Citation rate is the percentage of AI conversations in which a brand is named as a relevant answer. The metric is measured across a representative buyer prompt set run weekly against ChatGPT, Claude, Gemini, DeepSeek, and Perplexity. OnlyAEO's standard methodology rolls the weekly citation rates into a monthly average reported by query type and AI model.

The structure has all four elements: bolded term, one-sentence functional definition, two-sentence elaboration, named source (OnlyAEO's standard methodology). AI models routinely cite the full block verbatim when readers ask "what is citation rate".

Why glossaries compound

A brand that publishes a complete glossary of its category's terms earns disproportionate citation lift. Each definition becomes its own citable surface. The glossary becomes the brand's most cited page over time.

The cost of writing a glossary is roughly two hours per ten terms once the template is set. The citation lift compounds over years. Glossaries are one of the highest ROI assets in an AEO program.

Common definition failure modes

The patterns that fail most consistently are:

• Hedged definitions. "Citation rate generally refers to how often a brand is mentioned" is not citable because it does not commit to a specific definition. AI models prefer definitions that commit.

• Definitions that depend on other undefined terms. A definition that uses three category-specific terms without defining them is uncitable on its own. Definitions should stand alone or link to their dependencies.

• Definitions that bury the term inside the body. AI extraction is helped by structural identification. A definition where the term appears once in the third sentence is harder to extract than a definition where the term is bolded at the start.

Fixing these three patterns lifts citation rate on existing glossary pages without adding terms.