Hemorrhagic diathesis is a medical condition in which a patient is prone to bleeding much more than normal. This can be the result of a genetic disease such as hemophilia, viral diseases such as yellow fever, or the result of malnutrition such as the lack of vitamin C (resulting in scurvy) or of vitamin K. It can also be a symptom of acute leukemia.

From the science dictionary at http://biotech.icmb.utexas.edu/