MELD: Acronym for Model End Stage Liver Disease. A disease severity scoring system for adults with liver disease, designed to improve the organ allocation in transplantation based on the severity of liver disease rather than the length of time on the waiting list. The MELD score is based only on laboratory data in order to be as objective as possible. The laboratory values used are a patient's creatinine, bilirubin, and international normalized ratio, or INR (a measure of blood-clotting time). The pediatric version of MELD is called PELD.