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Tawny-OWL allows construction of OWL ontologies, in a evaluative, functional and fully programmatic environment. Think of it as the ontology engineering equivalent of R. It has many advantages over traditional ontology engineering tools, also described in a video introduction.

  • An interactive shell or REPL to explore and create ontologies.
  • Source code, with comments, editable using any of a range of IDEs.
  • Fully extensible -- new syntaxes, new data sources can be added by users
  • Patterns can be created for individual ontologies; related classes can be built easily, accurately and maintainably.
  • A unit test framework with fully reasoning.
  • A clean syntax for versioning with any VCS, integrated with the IDE
  • Support for packaging, dependency resolution and publication
  • Enabled continuous integration with both ontology and software dependencies

Tawny-OWL is implemented as a domain-specific language but built over a full programming language called Clojure. Many of the features described (REPL, patterns, unit tests, extensibility) derive directly from the Clojure language, or from general-purpose programming tools (IDEs, versioning, continuous integration). The core ontology features are implemented directly using the OWL API. These features are, therefore, industry strength, standards-compliant and well-supported independently of the Tawny-OWL developers.

OWL is a W3C standard ontology representation language; an ontology is a fully computable set of statements, describing the things and their relationships. They are used, mostly notable in biomedicine, to describe complex areas of knowledge such as genetics or clinical terminology, but can describe anything, including e-commerce. For more tutorial information, please see

A full-length manual is also available. The original, slightly older getting started document is available.

For the Clojure developer

Tawny-OWL is predominately designed as a programmatic application for ontology development, but it can be used as an API. OWL ontologies are a set of statements about things and their relationships; underneath these statements map to a subset of first-order logic which makes it possible to answer questions about these statements using highly-optimised reasoners.

Currently, the use of ontologies as a tool within general-purpose programming is relatively under-developed. Part of the intention behind Tawny-OWL is to embed ontologies deeply within a programmatic framework, to see whether ontologies are useful in this way.

Further information on the use of Tawny-OWL is available in the documentation.


I discuss the development of this code base in my journal. Two posts include one on the motivation and another on making the library more "lispy". All revelevant posts are categorised.


Tawny-OWL requires no installation per se and is used as any Clojure library. It is available from clojars, so just add:

[] to your project.clj file.

I use Leiningen 2 on the current version 16.04 Ubuntu and, occasionally, on Windows. Editing of both tawny-owl and the ontologies using it, is with Emacs 25 using Clojure mode and nrepl, currently both installed from their respective versioning systems. The library should not depend on this environment, however.


Phillip Lord, Newcastle University.

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The contents of this file are subject to the LGPL License, Version 3.0.

Copyright (C) 2012, 2013, Newcastle University

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this program. If not, see


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