Meningioma: A common type of slow-growing, usually benign brain tumor that arises from the dura, one of the meninges, the membranes covering the brain and spinal cord. A meningioma may occur wherever there is dura (the outermost of the three meninges), but the most common sites are over the cerebral hemispheres of the brain. Meningiomas are the only brain tumors that are more common in women than in men. They tend to occur in people between ages 40 and 60 but can occur at any age. A person may have several meningiomas. Very rarely do meningiomas become malignant. The symptoms depend on the location of the tumor. Treatment ranges from observation to neurosurgical resection.