The term 'Mater' (Brain Part) is composed of two parts, PIA (3 letters) and Dura (4 letters). The Pia mater is the innermost layer of the meninges, a protective membrane that surrounds the brain and spinal cord. It is a delicate and highly vascular membrane that adheres to the surface of the brain and spinal cord. The Dura mater is the outermost layer of the meninges and is a tough, fibrous membrane that provides protection and support for the brain and spinal cord. Together, the Pia mater and Dura mater form the Mater, which is the collective name for the two layers of the meninges.