Cancer: A condition characterized by the abnormal and often uncontrolled growth of cells, which can sometimes spread to other parts of the body. Cancer encompasses over 100 distinct diseases rather than being a single illness. It can affect any tissue in the body, manifesting in various forms depending on the area involved. Cancers are typically named after the cell type or organ where they originate. If a cancer metastasizes, the secondary tumor retains the name of the original (primary) tumor. The prevalence of specific cancers can vary by gender. Skin cancer is the most prevalent type for both men and women; however, the second most common cancer differs between the sexes. The frequency of a cancer does not necessarily correlate with its mortality rate. While skin cancers are often treatable, lung cancer remains the leading cause of cancer-related deaths among both men and women in the United States today. It's important to note that not all tumors are cancerous; benign tumors are non-cancerous, while malignant tumors are cancerous. Cancer is not a contagious disease.The term "cancer" derives from the Latin word for crab. Ancient peoples likely used this term to describe malignancies because of the way a malignant tumor can cling tenaciously to the tissues it invades, much like a crab. Cancer is also referred to as a malignancy or a malignant tumor, and is scientifically known as a neoplasm, meaning "new growth."