1. The tough outermost membrane of the three meninges or layers of connective body tissues that surround and protect the brain and the spinal cord: The dura mater is the strong and fibrous outer covering; while inside the skull, it comprises an outer and an inner layer and provides support for the substances of the brain.

While the dura mater is lining the inside of the skull, it is supporting the cranial sinuses or channels, and allows blood to be carried from the brain to the heart.

Folds of the dura mater partly separate the cerebral hemispheres from each other and the cerebrum (the largest and most developed part of the brain and the area where most conscious and intelligent activities occur) from the cerebellum (region of the brain that maintains posture and balance and the coordination of movements).

2. Etymology: from Latin dura mater; literally, "hard mother" and dura mater cerebri; "hard mother of the brain".