The term "acting out" corresponds to Freud's use of the German word "agieren" (as a verb and as a noun). It should be distinguished from the closely related concept of "passageà l'acte," inherited from the French psychiatric tradition and denoting the impulsive and usually violent acts often addressed in criminology.

"Acting out" refers to the discharge by means of action, rather than by means of verbalization, of conflicted mental content. Though there is this contrast between act and word, both sorts of discharge are responses to a return of the repressed: repeated in the case of actions, remembered in the case of words. Another distinction occasionally drawn is between acting out and acting in, used to distinguish between actions that occur outside psychoanalytic treatment (often to be explained as compensation for frustration brought on by the analytic situation, by the rule of abstinence, for example) and actions that occur...