A contraction of dunce cap (1840) and dunderhead (1625).
An idiot, numb skull, blockhead or dunce. One who does not understand the obvious results of a planned action.
Ah come on you Dunder Caps! Look at what renovations to the Vinoy hotel did for downtown St. Pete! The concerts, the promotions – at Vinoy Park. Please. If that isn’t an example of how to make money on a historic downtown venue I don’t know what is. Are all of you out of work construction workers?