Wikipedia
Freedict is a collection of free bilingual dictionaries, licensed under the terms of the GNU General Public License (GPL).
The primary format of the dictionaries is XML complying to the Text Encoding Initiative Guidelines. Most dictionaries have databases in the DICT format. Other occasionally available formats include Stardict, zbedic, Evolutionary Dictionary and Opendict. Some Linux distributions (such as Debian) provide the Freedict dictionaries as easily installable packages. StarDict can make a good front-end for daily use of Freedict.
As of November 2009, the project hosts 70 bilingual dictionaries of various sizes.
The dictionaries can be used via DICT clients (standalone and plugins, both locally and remotely), DICT WWW interfaces, and directly in a browser (source XML + CSS).