1. Pertaining to a disease that is characterized by extreme virulence and is exceptionally contagious or infectious: As a patient, Leroy was placed in the isolation ward as a result of the extremely malignant nature of his lung infection.
2. A reference to the tendency of becoming worse and the resistance to medical treatment; pertaining to cancerous development: Given the malignant nature of the growth in the Bill's stomach, the doctor was recommending radical surgery.
3. Relating to or referring to a threat to produce death; harmful; virulent: The term malignant primarily describes such ailments as a tumor which spreads from its original location to affect other areas of the body with potentially life-threatening results.
4. Characterized by an intense ill-will; keenly desirous of the suffering or misfortune of others generally: The dictator had a powerful and malignant influence on the lives of the citizens of his nation and that's why so many of them fled to neighboring countries.

A condition in which a disease or ailment is growing worse and resisting treatment: Mary's malignant cancer was diagnosed and there was no doubt that it would cause her death in a short time because no medical treatment was successful.

A tumor in the covering of the central canal of the spinal cord or the ventricles (chambers) of the brain: Jeff was diagnosed with a malignant ependymoma or a deadly cancer in both his spinal cord and in a section of his brain.

A serious type of skin cancer: Malignant melanoma takes place in the melanocytes, the cells that produce "melanin", the pigment that colors the skin, hair, and even the iris of the eyes.

Malignant melanomas causes cancers that occur and are most common in middle-aged and elderly people with pale skin who have been exposed to strong sunlight over many years.

The growth of malignant melanoma usually develops on exposed areas of skin, but it may take place under the fingernails or toenails and even in the eyes.

1. A personality type showing excessive love or approval of himself or herself: The psychiatrist diagnosed Jerry as exhibiting characteristics of malignant narcissism or an exaggerated sense of personal admiration.
2. Antisocial behavior: Mary had difficulties on the playground at school because she exhibited a form of malignant narcissism which was aggressive towards those who did not admire and praise her.
3. Ego-syntonic aggression or sadism directed against others including inhumane or barbarous killing: The police were alarmed at the repeated discovery of mutilated corpses and focused their search on a person who was known to be possessed with malignant narcissism and had recently escaped from prison.

The lymphocytes that produce antibodies which destroy bone tissue and cause overproduction of immunoglobulins: The malignant neoplasm of bone marrow leads to osteolytic lesions, hypercalcemia, anemia, renal damage, and increased susceptibility to infection.