- A malignant tumor of the central nervous system arising in the cerebellum especially in children.
Definition from: Merriam-Webster's Medical Dictionary by Merriam-Webster Inc.
- A malignant brain tumor that begins in the lower part of the brain and that can spread to the spine or to other parts of the body. Medulloblastomas are a type of primitive neuroectodermal tumor (PNET).
National Cancer Institute
See also Understanding Medical Terminology.