The term 'Brain Membrane' refers to the two protective layers that surround the brain and spinal cord. The outermost layer is called the Dura, which is a four-letter word derived from the Latin word for 'HARD'. The innermost layer is called the Piamater, which is an eight-letter word derived from the Latin words for 'TENDER' and 'mother'. Together, these two layers form the Brain Membrane, providing protection and support for the brain and spinal cord.