Meninges: The three membranes that cover the brain and spinal cord (singular: meninx).
The outside meninx is called the dura mater, and is the most resilient of the three. The center layer is the arachnoid membrane and the thin innermost layer is the pia mater. Inflammation of the meninges (meningitis) can occur due to bacterial infection.
See also meningitis article.