The first formal description of the waterfall model is often cited as a 1970 article by Winston W. Royce,[4][5] although Royce did not use the term "waterfall" in this article. Royce presented this model as an example of a flawed, non-working model.[6] This, in fact, is how the term is generally used in writing about software development—to describe a critical view of a commonly used software development practice.
http://en.wikipedia.org/wiki/Waterfall_model