Shoe width is denoted by an alpha system: A = narrow --> E = wide.
"C" is "technically the "average" width. However, most men who buy dress shoes rate comfort as important (or more important) than fashion. So, the reality is that most men wear a dress shoe with a "D" width. (As opposed to most women who, in complete defiance of reality, will wedge their foot in to an "A" width shoe.)
A shoe with an EEE width is very wide.