alert
adjectiveUK /əˈlɜːt/
US /əˈlɝːt/
Being awake and paying full attention to what is happening.
The guard stayed alert all night and noticed every sound.
OTHER MEANINGS
2. A warning or message that tells people about danger or something important.
The weather service sent an alert about the coming storm.
3. To warn someone about a possible problem or danger.
The teacher alerted the students to the fire drill.
4. Quick to notice and react to things.
She has an alert mind and solves puzzles fast.
5. A state of being ready to act or respond.
The soldiers were on alert during the night.