Malignancy

n.
  1. The state or quality of being malignant; extreme malevolence; bitter enmity; malice; disposition toward evil; intense ill will; as, malignancy of heart.
  2. Unfavorableness; evil nature.
  3. (Med.) Virulence; tendency to a fatal issue; as, the malignancy of an ulcer or of a fever.
  4. The state of being a malignant.