A fisheye lens is an extremely wide-angle lens that is purposely designed to have extreme barrel distortion.
Is there such a thing as a lens purposely designed to have pincushion distortion? What would that look like?
(Yeah, you can do it in software, but you already get better results from doing these things optically if you can.)
Answer
The opposite of a fisheye is a rectilinear lens.
You probably did not find one because your definition is wrong. Distortion of a fisheye lenses is not barrel distortion, it is that a different projection or mapping is obtained by design. Angles are usually preserved but not straight lines, unless they pass through the center of the frame.
A rectilinear lens on the other hand is designed to preserve straight lines, regardless of where they occur in the frame. This makes it impossible to map an angle of view close to 180 into a flat image.
Wikipedia has interesting diagrams showing the difference and even various types of fisheye lens projects.
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