Acronym for Missed Day Stress Syndrome.
Usually developed by math/geometry/calculus student when a single missed class causes a complete hole in their knowledge of the chapter. Syndrome can be brought on by a bitchy teacher who refuses to teach you at a different time, a book that describes everything in 40,000 words, or a friend who sucks at explaining their processes. The only known relief methods are to either fail the chapter or drop the class.
Patient: "Doc, I just, I missed a day and now I'm so behind! This section is used throughout the whole chapter! I can't do the rest without it! Ahh!!! HELP ME!!!"
Doctor: "I'm sorry, but I'm afraid you have MDSS... There's nothing we can do..."