I really like Dictionary.Com. Although the iPhone app is missing some of the power behind Dictionary.com on the Web--most notably, the translator and helpful articles it is still useful. From what I understand, More than 50 million people use Dictionary.Com and it is the world’s largest free online dictionary and mobile application. As a search-and-retrieve word application, however, this is a good start for those looking for a free reference app or who are trained to prefer Dictionary.com's experience. It's great!