1. A precise moment in time when a decision, event, or condition reaches a crucial or decisive point; a turning point
The critical instant in the negotiation came when both parties agreed to compromise.
O instante crítico na negociação chegou quando ambas as partes concordaram em fazer concessões.
2. In technical or scientific contexts, a specific moment when a system, process, or phenomenon reaches a threshold or critical state
The critical instant for the chemical reaction was when the temperature reached 100 degrees Celsius.
O instante crítico para a reação química foi quando a temperatura atingiu 100 graus Celsius.