The phrase traumatic encephalopathy has come to be used in two very different ways. On the one hand, there is the simple, noncontroversial English meaning: deterioration in cerebral function after trauma. On the other hand, one increasingly encounters the longer phrase chronic traumatic encephalopathy (CTE) as a term of art dissociated from its English meaning. In popular and even academic parlance, CTE has recently been translated as "a particular neuropathological profile sometimes observed using certain techniques on post-mortem examinations of the brains of persons who have sustained multiple concussive brain injuries (CBIs)." The present chapter reviews the history of the discovery of an association between exposure to multiple CBIs and both behavioral and brain change. It attempts to tabulate the subset of findings that seem comparable in an effort to tentatively identify a clinical syndrome. It proposes preliminary research diagnosis criteria, more for discussion than for adoption. The chapter, however, is admittedly incomplete (and possibly oblique to the truth) since theory and accumulating empirical evidence raise doubts about the validity of a single, unitary post-CBI encephalopathy.