EuroWordNet is a system of semantic network

Semantic network

A semantic network is a network which represents semantic relations among concepts. This is often used as a form of knowledge representation. It is a directed or undirected graph consisting of vertices, which represent concepts, and edges.- History :...

s for European languages, based on Wordnet

WordNet

WordNet is a lexical database for the English language. It groups English words into sets of synonyms called synsets, provides short, general definitions, and records the various semantic relations between these synonym sets...

. Each language develops its own wordnet but they are interconnected with interlingual links stored in the Interlingual Index (ILI).

Unlike the original Princeton WordNet

WordNet

WordNet is a lexical database for the English language. It groups English words into sets of synonyms called synsets, provides short, general definitions, and records the various semantic relations between these synonym sets...

, most of the other wordnets are not freely available.

Languages

The original EuroWordNet project dealt with Dutch, Italian, Spanish, German, French, Czech, and Estonian. These wordnets are now frozen, but wordnets for other languages have been developed to varying degrees.

License

Some examples of EuroWordNet are available for free. Access to the full database, however, is charged. In some cases, OpenThesaurus

OpenThesaurus

OpenThesaurus is an open source thesaurus project whose data is available under the GNU Lesser General Public License. It can be used directly online and with a free account users that are logged in can also add and alter entries. All entries have to be checked at least once before a release is made...

may serve as a free alternative.