Decleration: The sudden stop of the brain's forward motion when it hits the skull after an impact. This sudden stop tears the neuron connections and violently twists and jars the brain.

Dementia Pugilistica: Brain damage caused by cumulative and repetitive head trauma; common in career boxers.

Depressed Skull Fracture: A fracture which occurs when pieces of broken skull, press into the tissues of the brain.

Diffuse Axonal Injury: Widespread tearing of nerve fibers across the whole of the brain.

Diffuse Brain Injury: Widespread injury resulting from the brain forcefully hitting the inside of the skull bones in addition to being twisted.

Dura: A tough, fibrous membrane lining the brain; the outermost of the three membranes collectively called the meninges.

Dysarthria: An inability or difficulty articulating words due to emotional stress, brain injury, paralysis, or spasticity of the muscles needed for speech.

Dysphagia: An impairment which makes swallowing difficult; this often occurs as a result of a brain injury.