DefinedTerm Schema

DefinedTerm schema is a Schema.org entity type designed to mark up definitional content, telling search engines and AI systems that a web page provides a definition for a specific term or concept. It is implemented within a DefinedTermSet (a glossary or collection of terms) and includes properties for the term name, description, and optionally the broader vocabulary domain it belongs to. For glossary-style publishers, DefinedTerm schema is the most semantically precise markup available and directly supports answer engine citation for definitional queries.

How it works

A DefinedTerm schema block is added as JSON-LD to the HTML of the definition page. The ‘@type’ is set to ‘DefinedTerm’, with properties including ‘name’ (the term being defined), ‘description’ (a plain-text definition), and ‘inDefinedTermSet’ (pointing to the parent glossary or DefinedTermSet entity on the site). The DefinedTermSet entity can be declared on the main glossary index page. When Google or an AI RAG system crawls the page, the schema explicitly identifies the page as a definition, increasing its eligibility for definitional rich snippets and AI citation for ‘what is X’ query types.

Key facts

• Schema.org type: DefinedTerm is a subtype of Intangible in the Schema.org hierarchy; its parent is DefinedTermSet, which represents a glossary collection.
• Key properties: ‘name’ (the term), ‘description’ (the definition text), ‘inDefinedTermSet’ (the parent glossary), and ‘url’ (canonical page URL) are the most important properties to populate.
• AI retrieval signal: Perplexity, ChatGPT browsing, and Google AI Overviews all benefit from DefinedTerm schema when selecting pages to cite for definitional queries.

For builders

WikiWalls glossary entries are a textbook use case for DefinedTerm schema. Implementing it on every entry creates a machine-readable signal that the entire site is a structured definitional reference, not just a collection of articles. The practical implementation involves adding a JSON-LD block to the WordPress post template for glossary entries, programmatically populating the ‘name’ from the post title and ‘description’ from the post excerpt. This automation ensures all 160+ entries carry the schema without manual per-post maintenance, and it compounds in value as the glossary grows into a recognized topical authority.

Sources

• Schema.org. DefinedTerm type specification. schema.org
• Schema.org. Full type hierarchy and DefinedTerm specification. schema.org
• Google. Introduction to structured data. developers.google.com
• W3C. JSON-LD 1.1 recommendation. w3.org
• JSON for Linking Data. Learning resources and primer. json-ld.org