Several terms in the scientific literature about posttraumatic stress disorder are used with different meanings in studies conducted by different authors. Words such as trauma, violence, catastrophe, disaster and barbarism are often used vaguely or confusingly, and their meanings change in different articles. The lack of conceptual references for these expressions complicates the organization of literature. Furthermore, the absence of clear concepts may be an obstacle to clinical treatment because the use of these words by the patients does not necessarily point to a diagnosis of posttraumatic stress disorder.