http://www.w3.org/2006/03/wn/wn20/instances/ contains an RDF representation of WordNet 2.0. This project was created by the Semantic Web Best Practices and Deployment Working Group, part of the W3C Semantic Web Activity. For details, see "RDF/OWL Representation of WordNet".
An RDF index of the 139,000 words, 191,000 word senses, and 115,000 synsets described here is returned to clients that issue an HTTP GET on the namespace URI without an Accept: header or with an Accept: header specifying "application/rdf+xml".
Concise Bounded Descriptions of each resource are available from the resource URI; again, clients must either omit the Accept: header or specify its value to include "application/rdf+xml".