idiopathic thrombocytopenic purpura (ITP)/ĭd-ē-ō-PĂTH-ĭk thrŏm-bō-sī-tō-PĒ-nĭk PŬR-pū-ră/

disorder with severe platelet deficiency resulting in abnormal blood clotting, marked by tiny purple bruises (purpura) under the skin