Why Gellish

  • Gellish provides a standard for expressing information in a computer interpretable and system independent way that enables exchange and integration of data among multiple sources. It consists of a family of formalized natural languages, including Formal English, Formal Dutch and other formalized natural language variants. It is supported by:
    • A consistent methodology for semantic modeling of information.
    • A common language definition, in the form of a computer interpretable taxonomic dictionary-ontology with a scope of a natural language that enables expressing and interpreting information in a system independent way.
    • Reusable software tools that support system independent data exchange between application systems of various parties.

The objectives of the methodology, language and tools are:

  • To enable interoperability of systems and information integration, through
    • System independent information models.
    • A standardized formalized natural language for expressing information, knowledge, requirements as well as queries and responses.
    • A universal data exchange format, supported by software tools.
    • Synonyms, homonyms, proprietary terminology and automated translation.
  • To enable applying logic reasoning on data, knowledge and requirements, for
    • Intelligent searching,
    • Computer augmented design, fabrication and maintenance,
    • Computer augmented verification of deliverables versus requirements and knowledge.
  • To simplify implementations of system interfaces and to generalize user interfaces.
Link to questions about Semantic Modelling or the Gellish language(s)

Registered users have access to

  • A wiki guide on the expression of information in one of the formalized natural languages and the exchange and interpretation of messages in such a formal language. This includes data as well as queries and responses. The guide applies the Gellish Semantic Modeling Methodology.
  • A free Entry Edition of the Gellish Formal English language definition and various documents with application examples.
  • The free Gellish Communicator software (available via Github.com). This is a reference application, providing an example database implementation, source code, usage examples, data verification, searching in data and documents and a generic user interface.


  1. Language definition

    • Taxonomic Dictionary-Ontology

      The taxonomic dictionary-ontology consists of computer interpretable definitions of concepts, a vocabulary and relations between the concepts, arranged in the form of a taxonomy and ontology.The source data is suitable for being imported in Gellish enabled database systems, providing them with the language definition as a basis for expressing and interpreting information in the formal languages and for the application of logic reasoning.

      The Entry Edition of the taxonomic dictionary-ontology is free of charge available via the download area or together with the Entry Edition of the Gellish Communicator reference application, which is free of charge available from GitHub as well.

      The Professional Edition of the taxonomic dictionary-ontology of Formal English and Formal Dutch can be licensed on request.

    • Gellish Syntax (free of charge)

      The Gellish Syntax document defines an expression format for universal data exchange between systems. It also defines a large number of (optional) contextual facts, such as approval status, date-time of validity, author, etc. It also enables the use of multiple languages. The format enables expressing and interpreting base expressions as well as their contextual facts.

  2. Semantic Modeling Methodology book

    The book ‘Semantic Information Modeling Methodology‘ describes a systematic approach for expressing information, knowledge about possibilities, requirements in explicit contexts and definitions, while using a Gellish formal language. The book is illustrated with many practical examples.

  3. Semantic Modeling Language book

    The book ‘Semantic Information Modeling in Formalized Languages‘ explains how the formal languages of the Gellish family are defined and how they can be extended in such a way that the languages enable universal information exchange and interoperability of systems. The book is also available as eBook.

  4. Formalized Natural Languages book

    The book ‘Formalized Natural Languages‘, Definition and Application of Universal Information Modeling Languages’ (2014). This is the 2nd edition of ‘Gellish, a Generic Extensible Ontological Language’ (2005); PhD, Delft University of Technology. It describes the background of the Gellish family of formalized natural languages and Formal English in particular.

  5. Taxonomic Dictionary of Relations book

    The book ‘Taxonomic Dictionary of Relations’ is a printed version of the definitions of kinds of relations and their denoting phrases and inverse phrases that form the core of the definition of the Gellish family of formalized languages. The relation types are also suitable to be used as standard kinds of relations (properties) in RDF/OWL based data exchange (the book is also available in Dutch). The Formal English base ontology is the computer interpretable version of the book content. The Taxonomic dictionary of relations is also described and available via the dictionary page of the formalenglish.net website.


  • Information Management and Information Maturity Assessment Guide

Benefits of formalized languages

A break-through for interoperability

Formalized languages, such as Formal English and Formal Dutch (Formeel Nederlands) are a form of standardized computer interpretable subset of natural languages. Their definition includes a formal syntax (expression format) and an electronic Taxonomic Dictionary-Ontology. They enable expressing information, knowledge and requirements in a human and computer interpretable way that is ‘neutral’ and system independent. A formal language has an unlimited scope, in contrast to most conventional data models (databases) that have a fixed and limited scope. Gellish formalized languages are standardized formal subsets of natural languages. Their native syntax enable presentations in a tabular form, suitable for databases and data exchange messages. Other formats are also possible, such as RDF/XML. Gellish is compliant with ISO 16354 and an RDF implementation of Gellish is being standardized as ISO 15926-11.

Application of a formal language, such as Formal English, enables real interoperability or integration of data from different sources. It also enables integration of data, documents, and 2D drawings and 3D models. The language is generally applicable and is extensible. Its main application area’s are: the creation of compatible and consistent databases such as for system independent Product and Process Models, Facility Information Models (FIMs), Building Information Models (BIMs), product catalogs as well as knowledge and requirements, including business rules. Furthermore, it enables smooth data exchange between systems and business parties and eliminating costly data conversions in case of data migration and data integration. It is also applicable for development and application of electronic Dictionaries, Taxonomies, Thesauri and Ontologies.

The definition of Gellish Formal English, including the taxonomic dictionary-ontology is available for licensees via the webshop. A subset is available free of charge via the Gellish project on GitHub. Gellish can be used and implemented in various ways, including in conventional SQL database systems, or in XML, or in RDF, OWL or in simple JSON or CSV files or as spreadsheet tables. Gellish formal languages are ’embedded languages’, which means that they do not need a meta-language for their definition or interpretation.

Formal Language variants

Formal English and Formal Dutch (Gellish Formeel Nederlands) are examples of language variants from the Gellish family of formalized languages. Each concept in any of the formal languages in the family is represented by a unique identifier (a Gellish UID) which is an arbitrary language independent number or a (public or private) code preceded by a prefix. Translations of terms and phrases in various languages share the same UIDs. Thus different Gellish variants share the same concepts and kinds of relations, because their UIDs are identical although their terminology is different. This enables automated translation of Gellish expressions and models between natural languages for which formal dictionaries are available.
For example, Gellish formal domain dictionaries are available for Waste Water Terminology in English, French, German and Dutch conform the terms in ISO 16323.

Free available downloads:

  • The Gellish Syntax and Contextual Facts document includes a definition of the Gellish Expression Format as well as the definition of the Gellish Contextual Facts. See also an accompanying XML Schema of an earlier version.
  • An example of a Semantic Information Model of a road network, available in Gellish Formal English as well as in Formal Dutch (Formeel Nederlands).
  • An example of information about electric cables, including also catalogue data from various suppliers.