Glatt Or Not?

There are words that lose their original definition over time and take on a different meaning. This is certainly true of Yiddish words that have become standard in our vocabulary. Heimeshe cake is literally homemade cake. Sounds delicious, right? There is a store called “Heimeshe Printing”; does this mean they produce brochures that look like they were made by a six-year-old? Would you buy from a store called Heimeshe Vacuum? Do you really want a vacuum made out of Lego?
Another phrase that has lost its meaning is glatt kosher. The daf discusses all the various defects that can render an animal treif. It is biblically forbidden to consume the meat from an animal that had certain physical defects, even if the animal was properly slaughtered. The Mishnah lists 18 such defects, but the Gemara adds many more. They range from a hole in the membrane surrounding the brain all the way to problems with the intestine.
As a matter of practical halachah, we rarely check all the internal organs of a cow to make sure that there are no defects. We rely on the principle of rov beheimos einan treifos—the majority of animals are not treifos—and therefore we do not have to check each individual organ and we can assume it is part of the kosher majority. However, we do have an obligation to check those organs in which it is common to find defects. Since it is common to find lesions on bovine lungs, we have an obligation to check them.