A cell that keeps dividingA tumor is an abnormal growth of tissue resulting from uncontrolled, progressive multiplication of cells and serving no physiological function; a neoplasm. Can cause cancer!
The term "Tumor" derives from latin, and dates back to the time of Hypocrates, Father of the Hypocratic Oath, and who most historians credit with the formation of the Medical Theory. Unfortunately, Hypocrates didn't have the same knowledge we have today (he thought the brain was a mucus secreting organ, given its slimy texture and proximity to the nose!). In his day, illness was "rated" using the following terms: "Tumor" which equalled swelling "Callor" which was an indication of how red an injury was and, "Dolor" which was an indication of the heat produced by an injury. Early physicians considered the presence of all three of these to be a reliable indicator of an illness or an injury (turns out, they were on to something here! Ever twist your ankle? You had all three!) These days you don't hear much about Callor and Dolor, but we do here "Tumor". Unfortunately, it's true meaning has been subverted by the presence of Cancer in our lives, and many people think the two terms are equal. In reality, not all tumors are cancer, and not all cancers form tumors (think Leukemia). A tumor is really just a swelling of tissue where tissue is not usually swollen. Does that mean if you have a sore throat and your mom checks your "glands" and finds them swollen that you have a tumor? not really, just localized swelling caused by an infection.
a big thing that hurts, sometimes cancerous , sometimes not (malignant or benign)
Tumor refers to an abnormal growth of tissue, whether benign or malignant.