Crisis

Part of speech: noun (n.)

1. The point of time when it is to be decided whether any affair or course of action must go on, or be modified or terminate; the decisive moment; the turning point. This hour's the very crisis of your fate. Dryden. The very times of crisis for the fate of the country. Brougham.

2. That change in a disease which indicates whether the result is to be recovery or death; sometimes, also, a striking change of symptoms attended by an outward manifestation, as by an eruption or sweat. Till some safe crisis authorize their skill. Dryden.