Benign refers to a condition, tumor, or growth that is not cancerous. This means that it does not spread to other parts of the body. It does not invade nearby tissue. Sometimes, a condition is called benign to suggest it is not dangerous or serious.
In general, a benign tumor grows slowly and is not harmful. However, this is not always the case.
A benign tumor may grow big enough or be found near blood vessels, the brain, nerves, or organs. As a result, it can cause problems locally without spreading to another part of the body. Sometimes, these problems can be serious.
The opposite of benign is malignant.
Hall JE. Genetic control of protein synthesis, cell function, and cell reproduction. In: Hall JE, ed. Guyton and Hall Textbook of Medical Physiology. 13th ed. Philadelphia, PA: Elsevier; 2016:chap 3.