Definition · Plain-language
Data dictionary
A data dictionary is a centralised repository of metadata that records the definitions, formats, relationships and permitted values of an organisation’s data elements, giving everyone a shared, authoritative reference.
The step most authors miss
Doing CRediT right? Don’t stop at the statement.
A CRediT statement credits you inside one paper. The recognition CRediT was built for happens when those roles are tied to you, persistently. Sign in with your ORCID — free — and claim your CRediT contributions on casrai.org, the home of the standard. They become a verified, portable part of your identity, not a line that disappears into one PDF.
Free: claim your contributions, then export a journal-ready CRediT statement, schema.org structured data, JATS XML, CSV or BibTeX — and preview your public profile. A membership publishes that profile publicly and verifies the journals you serve.
What a data dictionary records
A data dictionary captures, for each data element, a precise definition, its data type and format, its relationships to other elements and its permitted values or value range. It may also record ownership, source system and any business rules. The purpose is to remove ambiguity: where one team’s revenue might differ from another’s, the dictionary fixes a single agreed meaning. It is a foundational metadata artefact that supports consistent reporting, integration and analysis across systems.
Relationship to ISO 11179
The international standard ISO/IEC 11179 describes metadata registries and a structured way to specify and register data elements so they are unambiguous and reusable across organisations. A data dictionary applies the same idea at the organisational level: it is, in effect, a registry of agreed data-element definitions. Aligning a dictionary with these registry principles — clear naming, definitions and permitted values — makes the organisation’s data more interoperable and easier to share with partners and standards-based systems.
Dictionary, catalogue and glossary
These terms overlap but differ in focus. A data dictionary describes data elements at a structural level — fields, types and allowed values. A business glossary defines business terms in plain language. A data catalogue is a broader inventory of data assets, often pulling in dictionary, glossary and lineage metadata to aid discovery. In practice a mature organisation maintains all three, with the data dictionary providing the detailed, element-level definitions the others reference.
Key facts
At a glance
- Definition: a centralised repository of data-element metadata
- Records: definitions, data types, formats, relationships, allowed values
- Purpose: a single authoritative meaning for each field
- Related standard: ISO/IEC 11179 metadata registries
- Distinct from: a business glossary (plain-language terms)
- Supports: consistent reporting, integration and analysis
Common misconceptions
What people often get wrong
Often heard: A data dictionary and a data catalogue are the same thing.
Actually: A data dictionary describes individual data elements — their definitions, types and allowed values. A data catalogue is a broader inventory of data assets for discovery, which often references dictionary content.
Often heard: A data dictionary is just technical documentation for developers.
Actually: It serves business users too, fixing agreed definitions and permitted values. Its value is shared meaning across business and technical teams, not only schema documentation.
Often heard: Once built, a data dictionary rarely needs updating.
Actually: Definitions, systems and rules evolve. A dictionary must be governed and maintained, usually by data stewards, or it becomes inaccurate and people stop trusting it.
Going deeper
