What is DefinedTerm Schema

Full definition

DefinedTerm is a Schema.org type that represents a word or phrase with a formal definition within a specific domain or controlled vocabulary. It is a subtype of Intangible and is designed to be used alongside DefinedTermSet, which represents the collection or glossary that the term belongs to.

The primary properties of a DefinedTerm entity are name (the term itself), description (the human-readable definition), termCode (an optional identifier or code used within the vocabulary system), and inDefinedTermSet (a reference to the DefinedTermSet that groups this term with related terms). The DefinedTermSet entity in turn carries a name, an optional description, and can have a url pointing to the glossary page itself.

This type is intentionally lightweight. It is not about describing a business or service—it is about declaring that a specific page or section of a page is the canonical source for the definition of a named concept. Search engines and AI reasoning systems can use this to resolve ambiguity when the same phrase has different meanings in different contexts.

Why it matters in 2026

Generative AI systems—including Google AI Overviews and large language models used in search—need to identify authoritative definitional sources to resolve terminology accurately. A glossary page that lacks structured data is treated as ordinary content. A page that uses DefinedTerm markup explicitly declares itself as a definitional authority for a concept, which increases the likelihood it will be cited when an AI system needs to define that term.

For industry-specific sites in sectors such as construction, home improvement, or legal services, specialized vocabulary often does not appear in general knowledge bases. DefinedTerm markup bridges that gap by making domain-specific definitions machine-readable without requiring the content to be indexed in a general encyclopedia.

How to implement

1. Identify the term being defined and confirm that the page (or a distinct section of the page) is dedicated to that definition.
2. Decide on a DefinedTermSet identifier for the glossary or vocabulary the term belongs to. This can be the URL of the glossary index page.
3. Add a <script type="application/ld+json"> block with @type set to "DefinedTerm".
4. Set the name property to the exact term being defined (matching the visible heading on the page).
5. Set the description property to a concise, accurate definition of the term.
6. Add the inDefinedTermSet property referencing the parent DefinedTermSet. This can be a full nested object or a simple URL string pointing to the glossary collection page.
7. Optionally add termCode if the term has an identifier within your taxonomy or a reference classification system.
8. Validate the markup with Google's Rich Results Test and the Schema.org validator at validator.schema.org to confirm syntactic correctness.

Example

{
  "@context": "https://schema.org",
  "@type": "DefinedTerm",
  "name": "Schema Markup",
  "description": "A structured data vocabulary added to web pages using JSON-LD, Microdata, or RDFa to help search engines and AI systems understand the meaning and type of content on the page.",
  "inDefinedTermSet": {
    "@type": "DefinedTermSet",
    "name": "SEO and Structured Data Glossary",
    "url": "https://example.com/glossary"
  }
}

Related terms

Schema markup, FAQPage schema, HowTo schema.