http://dictionary.reference.com/search?q=wiki
wiki
<communications> A collaborative web site comprised of the
perpetual collective work of many authors. Similar to a web
log in structure and logic, a wiki allows anyone, using a
web browser, to edit, delete or modify content that has been
placed on the web site including the work of other authors.
In contrast, a blog, typically authored by an individual, does
not allow visitors to change the original posted material,
only add comments.
The term can also refer to the software used to create the
site. Wiki wiki means "quick" in Hawaiian. The first wiki was
created by Ward Cunningham in 1995.