Friday, November 27, 2015

Taxonomies and Terminologies

The current specialties of taxonomy management and terminology management have different histories and serve different purposes, but they are in fact closely related, and taxonomies and terminologies can be linked to share knowledge. At the annual Taxonomy Boot Camp conference in Washington, DC, earlier this month I met a terminologist attendee (Beate Früh of Büro b3) from Germany, who explained to me that the fields are quite similar, and that’s why she was attending a taxonomy conference. Also at the conference I met a vendor of a new software company (Jochen Hummel, CEO of Coreon), whose product provides both taxonomy and terminology management.

As with the field of taxonomies and taxonomy management, there are varying definitions of terminologies and terminology management.  The original meanings of both taxonomy and terminology are as fields of study, with taxonomy being the study of naming and classifying and terminology being the study of terms and their use. More commonly though, we refer to taxonomies and terminologies as sets of terms or concepts for a particular subject area or purpose.

Definitions of terminology include “technical or special terms used in a business, art, science, or special subject” (, and a “set of designations belonging to one special language” (ISO 1087-1:2000, 3.5.1), with “each designation representing a concept” ISO 25964-2:2013. According to International Information Centre for Terminology (InfoTerm): "The systematic organization and definition of concepts is called terminology management – which also includes classification.” (T.E.R.M.I.N.O.L.O.G.Y. PDF)


There are several differences between taxonomies and terminologies. The most obvious difference is that taxonomies have hierarchical relationships between the terms/concepts so as to create an overall hierarchical structure, and terminologies generally do not. Other differences are that terminologies contain more detailed terms than are found in a taxonomy for a comparable subject area.  Furthermore, while taxonomies are limited to nouns and noun phrases (including verbal nouns), terminologies may contain some specific adjectives. Terminologies generally include definitions for every term, which is not so typical for taxonomies. Many terminologies are used  to support foreign language translation, so there are usually foreign language equivalents for every term, something found in only a small minority of taxonomies. In general, there is more data for a term in a terminology than in a taxonomy.

The most significant difference between taxonomies and terminologies is how they are used. Taxonomies serve information retrieval, through a combination of indexing/tagging use and browsing/navigation and/or search support. Rather than serve information retrieval, the main purposes of terminologies are to support standard use of terms, especially technical terms, with agreed-upon meaning for creating technical documentation and for foreign language translations. Translation has historically been the field of greatest use of terminologies. As such, many terminologists have a background in translation or linguistics. The co-authors of a leading book in the field of terminology, Handbook of Terminology Management, are both professors of translation.

Another difference is in regional use. Taxonomies are especially widely used in the United States and other English-speaking countries, while growing elsewhere too, whereas terminologies are more widely used in Europe and bilingual countries such as Canada. Member organizations of Infoterm, the independent international association focused on terminology, include numerous organizations in Europe, a few in each of Africa, Asia, Latin America, and Canada, but there are no organizations in the United States.

Finally, there are a greater number of standards for terminologies. There are a large number of currently published standards of ISO committee 37 for Terminology and Other Language and Content Resources, including five standards of the Principles and Methods subcommittee, 14 of the Terminographical and Lexicographical Working Methods subcommittee, and five standards of the Systems to Manage Terminology, Knowledge and Content subcommittee, including ISO 30042:2008 TermBase eXhange (TBX). For taxonomies, on the other hand, standards are fewer, or, if considering specifically taxonomies, there actually are no standards, as the most relevant standards are for thesauri (ISO 25964 or ANSI/NISO Z39.19), ontologies (OWL, based on RDF), or more broadly web-based knowledge organization systems(SKOS).


Despite their differences, taxonomies and terminologies both are kinds of vocabularies or controlled vocabularies (depending on how “controlled vocabulary” is defined, the topic of my next blog post). The international standard ISO 25964 Thesauri and interoperability with other vocabularies, (part 1 in 2011 and part 2 in 2013) discusses the following “other” vocabularies (as listed in its table of contents): classification schemes, taxonomies, subject heading schemes, ontologies, terminologies, name authority lists, and synonym rings. Thus, terminologies are listed right along with taxonomies and ontologies. The United States standard ANSI/NISO Z39.19-2005 Guidelines for the Construction, Format and Management of Monolingual Controlled Vocabularies, however, does not include terminologies in its more limited scope: “Controlled vocabularies covered in by this Standard includes lists of controlled terms, synonyms rings, taxonomies, and thesauri.” (Section 2 Scope).

The most important similarity is that both taxonomies and terminologies refer to terms and unique concepts and not to mere words. As such, they often include and bring together synonyms or other variants to disambiguate concepts. While terminologies don’t characteristically have relationships between terms, they sometimes do.


Due to these similarities, it is quite feasible to have connections, links, mappings, etc., between terms in a taxonomy and in a terminology.  Taxonomies and terminologies for internal content within the same organization will have a lot of overlap, so it makes sense to leverage the same knowledge bases and either reuse the same terms in taxonomies and terminologies or at least link/map the equivalencies, both to save effort and to ensure consistency of understanding across and organization. ISO 25964-2 Thesauri and interoperability with other vocabularies includes a section on guidelines for the interoperability between thesauri (and, by extension, taxonomies) and terminologies:
  • Concepts may be mapped between a thesaurus and a terminology, and should follow the same methods and best practices as mapping between two thesauri (22.3.2)
  • Terminologies are useful as sources for concept of terms when building or maintaining a thesaurus. They can also be referred to when writing scope notes. (22.3.3)
  • A search thesaurus or synonym ring may be built using a combination of a thesaurus and a terminology. (22.3.4)

Hopefully, more organizations will be developing both taxonomies and terminologies where they are lacking and also build connections between the two.

Find out more about terminologies