Imam al-Shafi'i (may Allah have mercy on him) says: The very first wound is al-harisah, in which the skin splits a little; from it comes the expression 'harasa al-qassar al-thawb' (the fuller tore the cloth). After it is the wound al-badi'ah, in which the flesh is cut and the part beneath the skin becomes exposed. Then al-mutalahimah, which is the wound that cuts into the flesh but is not very deep. After it is al-simhaq; the simhaq is a thin veil between the bone and the flesh, like a membrane, and when the wound reaches this membrane but the bone does not become visible, it is a simhaq, and al-miltah is also a name for this same wound. Al-mudihah is the wound that tears through this membrane too and exposes the bone; al-hashimah is one in which the bone is broken; al-munaqqilah is the wound containing particles of bone; al-ma'mumah is the wound that reaches the brain; and al-ja'ifah is one that tears open the abdomen so that the wound reaches the intestines. Those that are less than al-mudihah are khudush (scratches), and for them there is settlement. Al-damiyah is a wound in which there is a scratch or a blow but blood does not flow.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16215