The term that means a tumor is the least dangerous is "benign."
A benign tumor refers to an abnormal growth of cells that is non-cancerous and does not invade nearby tissues or spread to other parts of the body. While it may still cause health issues depending on its size and location, a benign tumor is generally considered less dangerous than a malignant tumor, which is cancerous and can invade surrounding tissues and potentially spread to other areas of the body.