malignant
adj.adj. describes a disease, like cancer, that is very dangerous and likely to spread. It can also describe a person or feeling that is full of hate and wants to cause harm.
adj. tending to produce death or deterioration, specifically in a medical context regarding invasive tumors. In a figurative sense, it describes behavior or influences characterized by intense ill will or a desire to cause suffering.
The doctors confirmed that the tumor was malignant.
The biopsy results showed that the growth was malignant, requiring immediate surgery and follow-up treatment.
The dictator's malignant influence spread through the country, poisoning public discourse and turning neighbors against one another in an atmosphere of constant fear.
From Middle French malignant, from Late Latin malignans. See malign.
Often used predicatively after a linking verb like 'be' or 'become' in medical contexts.