Synonym for hypoprothrombinaemia ... <haematology> A congenital or acquired disorder of blood clotting where there is a deficiency of factor II (prothrombin), one of 20 necessary plasma proteins for normal blood coagulation. Acquired factor II deficiency may result from vitamin K deficiency, severe liver disease and anticoagulant drugs. ... S... Found on http://www.encyclo.co.uk/local/20973