pur·pu·ra / ˈpərp(y)ərə/ • n. Med. a rash of purple spots on the skin caused by internal bleeding from small blood vessels. ∎  any of a number of diseases characterized by such a rash: psychogenic purpura.DERIVATIVES: pur·pu·ric / pərˈpyoŏrik/ adj.

purpura (per-pew-ră) n. a skin rash resulting from bleeding into the skin from blood capillaries; the rash is made up of individual purple spots (see petechiae). Purpura may be due either to defects in the blood capillaries (nonthrombocytopenic p.) or to a deficiency of blood platelets (thrombocytopenic p.). idiopathic thrombocytopenic p. an autoimmune disease in which the platelets are destroyed, leading to spontaneous bruising. A mild acute form affects children; a more serious chronic form typically affects adults. See also thrombocytopenia, Henoch-Schönlein purpura.

purpura Purplish patches on the skin due to seepage of blood from underlying vessels. Physical injury, vitamin deficiencies, some allergies and certain drugs are among the causes.