What Is DefinedTerm Schema?
Short answer
DefinedTerm schema is structured data that marks a page as an authoritative definition of a specific term, with DefinedTermSet grouping a collection of them into a formal glossary. It's a niche, underused markup that fits definitional content exactly. This glossary runs on it.
DefinedTerm Schema explained
Schema.org's DefinedTerm type describes exactly what it sounds like: a word or phrase with a formal description, optionally belonging to a DefinedTermSet, the vocabulary or glossary it lives in. Marked up in JSON-LD, a term page declares its name, its description, its URL, and its membership in the set, and the set itself declares the collection.
The strategic logic is fit. Machines answering "what is X" questions are looking for definitional content, and DefinedTerm is the vocabulary's native way of saying "this page is a definition of X, maintained as part of a curated glossary." Most glossaries skip it, either because they're single mega-pages where per-term markup is awkward, or because the type is simply obscure. That makes it one of the few schema choices that's both precisely matched to an intent and rarely deployed by competitors.
It composes well with the rest of the stack: the term's description can mirror the page's extractable summary, dateModified carries the freshness signal, and author markup attaches a real person to the definition. None of that manufactures authority a page lacks. What it does is remove ambiguity about what the page is, for exactly the class of queries where being unambiguous is the job.
In practice
This one is self-demonstrating: the page you're reading carries DefinedTerm markup, and the glossary around it's wrapped in a DefinedTermSet. I chose that structure on purpose: per-term pages, each with its own schema, description, and reviewed date, because it maps to how answer engines retrieve definitions. When I recommend it to clients with glossaries or documentation, the reasoning is the same: if the page is a definition, say so in the language machines read.
Common misconception
People often assume generic Article schema covers definitional pages fine. DefinedTerm states the specific thing that matters, that this page defines this term, and specificity is the entire point of structured data.
Sources
Free email course: Smarter SEO for the Age of AI
Seven short lessons over three weeks: why clicks are falling even when rankings hold, and how to get AI systems to recommend your brand.
