(glee-OH-muh) 
A group of tumors that form in glial cells in the brain and spinal cord. Glial cells support and protect the nerve cells in the central nervous system and help them work the way they should. Gliomas can form anywhere in the brain or spinal cord and may be benign (not cancer) or malignant (cancer). They can also be low grade or high grade, determined by how abnormal the tumor cells look under a microscope and how quickly the tumor is likely to grow, spread, and come back after treatment. The three main types of gliomas are astrocytomas, oligodendrogliomas, and ependymomas. They can occur in both adults and children. Also called glial tumor.
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Figure
Anatomy of the brain showing the cerebrum, ventricles (with cerebrospinal fluid shown in blue), cerebellum, brain stem (pons and medulla), and other parts of the brain.