This section provides an introduction to the development of electronic Dictionaries-Taxonomies.

What is a Dictionary-Taxonomy or Ontology

A Dictionary-Taxonomy is some kind of dictionary in which the terms (lemma) have explicit relationships with other terms, whereas also the terms that are used in the definitions may be explicitly related to other terms. A Taxonomy is comparable to a Thesaurus, which traditionally is used in libraries for categorization and searching of books and documents. In a thesaurus the terms are related primarily by 'wider term - narrower term relations'. Taxonomies primarily contain 'subtype-supertype relations', also called 'specialization-generalization relations', which are a special kind of norrower term-wider term relations. If the terms in the dictionary-taxonomy are also related to each other by other kinds of relations we call the collection of expressions an ontology.

Furthermore, a smart Dictionary-Taxonomy makes a distinction between concepts and terms, because for many different terms (synonyms, abbreviations, codes, etc.) can be used to denote the same concept. Therefore, a smart Dictionary-Taxonomy will use unique identifiers (UIDs) to represent concepts and relate concepts to each other instead of terms. This enables that multiple terms are included in the dictionary to denote the same concept (possibly including possibly also terms in different languages).

With this in mind, a taxonomy can be defined more precisely as follows:
A taxonomy is a collection of concepts that are arranged in a subtype-supertype hierarchy, whereas each concept may be denoted by one or more terms (names or phrases). Furthermore, a Dictionary-Taxonomy also includes textual definitions of the concepts and is extended to become an ontology when it includes modeled definitions (also called definition models) and relationships of various kinds between the concepts that are referenced in those definition models.

This enables that multiple terms can be used to search for a particular concept and that the relations between the concepts can be used to find other concepts, definitions and also other knowledge, requirements and information about the concepts as far as is made available. The Dictionary-Taxonomy thus becomes a core access point for knowledge and information.

The latest version of the Gellish English Dictionary-Taxonomy can be purchased via the webshop. The 2008 version is free of charge available via the download area. It can be used as such, or can be used as a basis for developing proprietary extensions. It can also be used as part of the application of the Gellish Formal English language for which it is the dictionary.
Proprietary extensions typically will have the form of Domain specific Dictionaries-Taxonomies, of which the top concepts are taken from the Gellish Dictionary-Taxonomy, especially the TOPini section.

How to build a Dictionary-Taxonomy

High quality Dictionary-Taxonomies for various domains should satisfy a number of quality criteria.

The prime quality rule is that each concept shall be defined as being a subtype of another concept, which is called its supertype concept. This means that the definition of a supertype concept is also applicable to all its subtype concepts. It also means that definitions, knowledge and requirements about concepts are "inherited" to all their subtype concepts. For example, when the Gellish English Dictionary-Taxonomy contains that a motorway is a subtype of road, then software can conclude that government rules for roads in general) are also applicable for motorways. This enables that there is no need to respecify that for the subtypes of road again. Furthermore rules that only apply to motorways should be related to the concept motorway (and not to road).

Further guidelines on building high quality dictionary-taxonomies are available via the webshop, in the full article (for licensees only) and in the document: the Gellish Modeling Methodology - Part 2: Creation of Domain Dictionaries & Taxonomies. Those guidelines enable that that various domain dictionary-taxonomies can be integrated into one consistent whole, because they are made conform a consistent method, whereas they are expressed in a common language that is computer interpretable as well as system independent.