What is the common term for the abnormally reduced number of platelets in the blood?

The condition characterized by an abnormally reduced number of platelets in the blood is known as thrombocytopenia. This term is derived from the root "thrombocyte," which refers to platelets, and the suffix "-penia," meaning a decrease or deficiency. Platelets are essential for blood clotting, and a lower-than-normal platelet count can lead to increased bleeding and difficulties in blood clotting. Thrombocytopenia can result from various factors such as bone marrow disorders, increased destruction of platelets, or certain medical conditions.

The other terms provided have distinct meanings that do not pertain specifically to a low platelet count. For example, thrombopathy refers to a dysfunction of the platelets, hematoma indicates a localized collection of blood outside of blood vessels, and hemophilia is a genetic disorder that affects the blood's ability to clot due to deficiencies in specific clotting factors. Each of these terms addresses different aspects of hemostasis and blood-related conditions, which emphasizes the specificity of thrombocytopenia as the term for reduced platelets.