The first ever wiki site was founded in year 1995 as an automated supplement to the PortlandPatternRepository. The site was immediately popular within the pattern community, largely due to the newness of the internet and a good slate of InvitedAuthors. The site was, and remains, dedicated to PeopleProjectsAndPatterns.
WardCunningham created the site and the WikiWikiWeb machinery that operates it. He chose wiki-wiki as an alliterative substitute for quick and thereby avoided naming this stuff quick-web. An early page, WikiWikiHyperCard, traces wiki ideas back to a HyperCard stack he wrote in the late 80's.
See also one of these links:
get some answers on the WikiWikiWebFaq
get to know more about the WikiHistory
"Wiki" now is now contained in Oxford Dictionary:
wiki • noun a website or database developed collaboratively by a community of users, allowing any user to add and edit content. — origin from WikiWikiWeb (1995), coined by the US programmer Ward Cunningham (b.1949), from Hawaiian wiki wiki ‘very quick’, reduplication of wiki ‘quick’.