Originally, however, treifa was a term for one of the categories of non-Kosher meat. The literal meaning of treifah is torn or mortally wounded. It is written, "Do not eat meat from an animal torn (treifa) in the field" (Exodus 22:30).
The rabbis interpreted this to mean that any animal or fowl which, as a result of a birth defect, disease or inflicted wound, suffers from a mortally defective organ or limb (or an animal close to death) may be considered a treif or non-kosher.
Thus, even when a kosher animal is slaughtered in a kosher way, the meat could be non-kosher if certain defects in the animal are found. Lesions, lacerations, broken limbs, missing or punctured organs, or the result of an attack by a larger animal are all defects that make an animal treif.
While once the term treif referred to the meat from an animal with certain defects, today treif is used for all non-kosher products.