“acute stress disorder: A transient anxiety disorder following exposure to a traumatic event, with a similar pattern of symptoms to post-traumatic stress disorder plus symptoms of disassociation (such as dissociative amnesia, depersonalization, derealization) but occurring within four weeks of the traumatic event. If the symptoms persist beyond four weeks, then a diagnosis of post-traumatic stress disorder may be considered.
[From the Latin acutus sharpened, from acuere, to sharpen, from acus a needle]”
Excerpted from: Colman, Andrew M., ed. Oxford Dictionary of Psychology. New York: Oxford University Press, 2003.