Malignant (definition of)

Malignant is a term used to describe cancer cells that grow, multiply and spread throughout the body, although it can be applied to any disease with a prognosis that worsens over time and becomes terminal. A cancer is technically known as a malignant neoplasm. In contrast, a benign tumor does not grow or spread - although it may become malignant later, or be a sign of a malignancy elsewhere.

Other diseases that may be described as malignant include mesothelioma (pericardial mesothelioma), hypertension, hyperthermia, neuroleptic malignant syndrome, and certain types of malaria.