Wiktionary is a Wikimedia Foundation project aimed in creating a multilingual free content dictionary in every language. This means each project seeks to use a particular language to define all words in all languages. It actually aims to be much more extensive than a typical dictionary, including thesauri, rhymes, translations, audio pronunciations, etymologies, and quotations. The project started in December 2002, and as of January 2008 is available in over 100 languages with over 3,000,000 entries in all. The largest language edition is French, followed by English, Vietnamese and Turkish. All four of them have more than 150,000 entries each, while 8 languages in total have more than 100,000 entries each. 61 other languages have at least 1,000 entries.
Wiktionary has been collaborating with the Wikimedia Commons. Many sound files have been uploaded to Commons, to provide Wiktionary and other projects with examples of pronunciation.
Source : WikimediaFoundation.org