—n. 1. a stage in a sequence of events at which the trend of all future events, esp. for better or for worse, is determined; turning point.
2. a condition of instability or danger, as in social, economic, political, or international affairs, leading to a decisive change.
3. a dramatic emotional or circumstantial upheaval in a person's life.
4. Med. a. the point in the course of a serious disease at which a decisive change occurs, leading either to recovery or to death.
b. the change itself.
5. the point in a play or story at which hostile elements are most tensely opposed to each other.
—adj. of, referring to, or for use in dealing with a crisis.