What is the name of Wikipedia's free dictionary sister project?

Wikipedia’s free dictionary sister project is Wiktionary. It is a multilingual, collaboratively edited reference work that explains words, phrases, names, and other linguistic terms.

Wiktionary was launched on December 12, 2002, making it one of the earliest Wikimedia projects created after Wikipedia. Its entries can include definitions, pronunciations, etymologies, inflected forms, usage examples, quotations, translations, and related terms. Because it is not limited by the space constraints of a printed dictionary, it can cover many languages and specialized forms of language.

The name is a blend of “wiki” and “dictionary.” Like Wikipedia, Wiktionary is written by volunteers and uses MediaWiki software. It is hosted and supported by the Wikimedia Foundation, but its editorial communities develop the entries themselves.

The alternatives describe different projects: Wikibooks focuses on collaboratively written books, Wikiversity provides learning materials and courses, and Wikiquote collects quotations. Wiktionary is specifically the dictionary and language-reference project.