1. swift and urgent response or intervention without delay
The fire department took immediate action when the alarm was triggered.
O corpo de bombeiros tomou ação imediata quando o alarme foi acionado.
2. in military or tactical contexts, an automatic response to enemy contact
Soldiers are trained to execute immediate action drills when encountering hostile fire.
Os soldados são treinados para executar procedimentos de ação imediata ao encontrar fogo inimigo.