A crucial or decisive point or situation; a turning point.
A traumatic or stressful change in a person's life.
A sudden change in the course of a disease, usually at which point the patient is expected to either recover or die.
A point in a drama at which a conflict reaches a peak before being resolved.
An unstable situation, in political, social, economic or military affairs, especially one involving an impending abrupt change.
The scheduled time for the start of some event, especially a military operation; H-hour.