Wiktionary is a project to create 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 May 2013 is available in over 150 languages with over 16,000,000 entries in all. The largest language edition is English, with 3,380,000 entries. Then Malagasy, French, Chinese, and Lithuanian follow. All four of them have more than 600,000 entries each, while 24 other languages have more than 100,000 entries each. 73 other languages have at least 1,000 entries.
Wiktionary works in collaboration with the Wikimedia Commons. Many sound files have been uploaded to Commons to provide Wiktionary and other projects with examples of pronunciation. (Our projects, Wikimedia Foundation )