1. most quick to notice and respond to danger or opportunity; most watchful and ready
Usage: superlative form of alert

Examples

• She was the alertest guard on duty that night.
• The alertest students noticed the error in the equation immediately.
• Among all the hikers, he remained the alertest to potential wildlife encounters.
• The alertest drivers avoid accidents by staying focused on the road.
• During the emergency drill, the alertest employees evacuated first.
• The security team’s alertest member spotted the suspicious activity.