Wiktionary (whose name is a blend of the words wiki and dictionary) is a multilingual, web-based project to create a free content dictionary of all words in all languages. It is available in 158 languages and in Simple English. Like its sister project Wikipedia, Wiktionary is run by the Wikimedia Foundation, and is written collaboratively by volunteers, dubbed “Wiktionarians”. Its wiki software, MediaWiki, allows almost anyone with access to the website to create and edit entries. Because Wiktionary is not limited by print space considerations, most of Wiktionary’s language editions provide definitions and translations of words from many languages, and some editions offer additional information typically found in thesauri and lexicons. The English Wiktionary includes a Wikisaurus (thesaurus) of synonyms of various words. Wiktionary data are frequently used in various natural language processing tasks.