1. the primary form of thrombocytopenia (rather than a shortage of platelets caused by other conditions such as tuberculosis or chemical suppression of bone marrow etc.);
WordNet (r) 3.0 (2006):
essential thrombocytopenia
n 1: the primary form of thrombocytopenia (rather than a
shortage of platelets caused by other conditions such as
tuberculosis or chemical suppression of bone marrow etc.)