Q. What does glatt kosher mean? Is there something wrong with regular kosher?
A. Glatt has come to be a code word for “strictly kosher”, but the term is often not used correctly. Glatt literally means “smooth” and applies to the lungs of an animal. It cannot therefore be applied to chicken, because their lungs cannot be inspected; to fish, which do not have lungs; or to bread, cake, oil, toothpaste, chocolate or soft drinks.
In relation to an animal, glatt means that external examination reveals no blemish, adhesion, etc., on the lungs. From the time of the ancient geonim it has been allowed (Tur, Yoreh De’ah 39) to shake the lung to see if a “false” adhesion will separate. Other authorities, especially Yosef Karo, oppose trying to remove an adhesion with one’s fingers.
The Sephardim follow Karo, and though the Ashkenazi authority, Moshe Isserles, allows an adhesion to be removed without tearing the underlying tissue, the custom has become widespread to follow the stricter opinion and to use only glatt meat. Some prefer the stricter opinion in relation to everything, but the technical term glatt is not appropriate in relation to anything other than meat.