Vigilant (adjective)

1. Alert and watchful, especially in order to prevent danger or disorder.
2. Actively engaged in seeking out and countering threats.

Origin:

Middle english, from latin vigilant-, vigilans, present participle of vigilare to keep watch, from vigil.

Examples:

1. The police officers were vigilant in their duties to maintain public safety.
2. The security guard was vigilant and noticed suspicious activity.
3. He was vigilant in protecting his family from harm.
4. The government is vigilant in monitoring the spread of the virus.
5. The city is vigilant in its efforts to combat crime.