vigilant
US /ˈvɪdʒ.əl.ənt/
UK /ˈvɪdʒ.əl.ənt/

1.
vigilante, alerta
keeping careful watch for possible danger or difficulties
:
•
The security guard remained vigilant throughout the night.
O guarda de segurança permaneceu vigilante durante toda a noite.
•
We must be vigilant against any threats to our freedom.
Devemos estar vigilantes contra quaisquer ameaças à nossa liberdade.