Do not let the word wiki in its name and the content being provided by users through a wiki engine fool you, wikipedia is not a wiki (for a variety of reasons) but this is a common misconception.
Let's just say that if openstreetmap had been called wikistreetmap and used a wiki engine, it would still be "a map of the world, created by people like you and free to use under an open license." and not a wiki.
So yes using wiki as a shorthand to refer to wikipedia is not only confusing but also wrong.
[1] : http://c2.com/cgi/wiki the original wiki
-edit- meatball[2] is a wiki, consumerium[3] is a wiki everything2[4] is not a wiki[5] and everything2 not being wikipedia[6] doesn't make wikipedia a wiki.
[2]: http://meatballwiki.org/wiki/ [3]: http://develop.consumerium.org/wiki/Main_Page [4]: http://www.everything2.com/ [5]: http://everything2.com/title/wiki [6]: http://www.everything2.com/title/Everything2%20is%20not%20Wi...