Wikipedia starts with a Hawaiian word, and that word came from an airport bus.
In 1995, programmer Ward Cunningham built a website that anyone could edit through a browser. He called it WikiWikiWeb and put it online on c2.com on 25 March 1995, according to Wikipedia. The name came from a trip to Hawaii. A Honolulu International Airport employee had told him to take the Wiki Wiki Shuttle, the bus that ran between terminals.
In Hawaiian, wiki means "quick," and the doubled form wikiwiki emphasizes it. A Fandom wiki page says Cunningham first considered calling the site "QuickWeb." Wikipedia's article says he chose "wiki-wiki" as an alliterative replacement for "quick," so the project would not end up as "quick-web."
The word then became a general term for any user-editable site. The Oxford English Dictionary listed "wiki" on 15 March 2007.
Wikipedia came out of a failed project. Jimmy Wales and Larry Sanger had launched Nupedia in 2000 as a free encyclopedia written by experts and peer-reviewed. It was slow, and History.com says it published only two articles in its first six months. They moved to the wiki model, and Wikipedia went live on 15 January 2001.
History.com credits Sanger with coining the name by combining the Hawaiian word for "quick" with "encyclopedia." Wikipedia's article on Sanger says the same, and quotes him calling it a silly name for what was at first a very silly project. The Writers' Centre Australia explainer says Wikipedia reached 20,000 articles in its first year.
So the site's name is a promise in two parts: quick, and comprehensive.