The definition of traumatic brain injury (TBI) has expanded to include mild TBI and postconcussive syndrome. This evolution has resulted in difficulty disentangling the physical trauma of mild TBI from the emotional trauma of posttraumatic stress disorder (PTSD). Advances in stress neurobiology and knowledge of brain injury at the macroscopic, microscopic, biochemical, and molecular levels call for a redefinition of TBI that encompasses both physical and emotional TBI. Conceptualizing a spectrum of TBI with both physical and emotional causation resolves the irreconcilable tangle between diagnostic categories and acknowledges overlapping forms of brain injury and shared systemic effects due to hormonal and inflammatory mediators. Recognizing emotional TBI shifts the interpretation of emotional trauma from a confound to a comorbid, related cause of brain injury. The mechanism of emotional TBI includes the intricate actions of stress hormones on diverse brain functions due to changes in synaptic plasticity, where chronically elevated hormone levels reduce neurogenesis, resulting in dendritic atrophy and impaired cognition. The overlapping effects of physical and emotional trauma are seen in neuropathology (ie, reduction of hippocampal volume in TBI and PTSD); fMRI (similar regional activations in physical and emotional pain); and systemic sequelae, including changes in proinflammatory cytokine levels and immune cell function. Accumulating evidence favors a change in the definition of TBI to encompass emotional TBI. The definition of TBI will be strengthened by the inclusion of both physical and emotional trauma that result in diverse and overlapping forms of brain injury with sequelae for physical and mental health.