Answer: CANCER.
Explanation: Cancer is a disease in which the cells of a tissue undergo uncontrolled (and often rapid) proliferation ( the process by which an organism produces others of its kind; breeding, propagation, procreation, reproduction.)
Some types of cancer cause rapid cell growth, while others cause cells to grow and divide at a slower rate.
The major types of cancer are carcinoma, sarcoma, melanoma, lymphoma, and leukemia.