Synonym: attentive, lively, nimble, on the job, prompt, ready, watchful, dull, slow, torpid. Similar words: dealer, ruler, clerk, killer, gallery, clergy, hitler, bowler. Meaning: [ə'lɜːt] 
n. 1. condition of heightened watchfulness or preparation for action 2. a warning serves to make you more alert to danger 3. an automatic signal (usually a sound) warning of danger. v. warn or arouse to a sense of danger or call to a state of preparedness. adj. 1. very attentive or observant 2. mentally responsive 3. not unconscious; especially having become conscious 4. (usually followed by `to') showing acute awareness; mentally perceptive.
n. 1. condition of heightened watchfulness or preparation for action 2. a warning serves to make you more alert to danger 3. an automatic signal (usually a sound) warning of danger. v. warn or arouse to a sense of danger or call to a state of preparedness. adj. 1. very attentive or observant 2. mentally responsive 3. not unconscious; especially having become conscious 4. (usually followed by `to') showing acute awareness; mentally perceptive. 
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1. Try to stay alert while driving at night.
2. You must be alert to the hidden danger.
3. Suddenly he found himself awake and fully alert.
4. All the Plymouth hospitals are on red alert.
5. She is alert to every sound and movement.
6. He is an alert boy.
7. Two alert scientists spotted the mistake.
8. The machine should help to keep the pilot alert.
9. The animal raised its head, suddenly alert.
10. We need to be alert to potential pitfalls.
11. The alert listener will have noticed the error.
12. He is a man alert in problem.
13. Alert readers may have noticed the misprint in last week's column.
14. His sudden disappearance triggered a red alert among his friends.
15. I'm not feeling very alert today - not enough sleep last night!
16. Be on the alert for anyone acting suspiciously.
17. Soldiers and police have been put on alert.
18. The troops were placed on full alert.
19. The bomb alert was raised soon after midnight.
20. Her expression was watchful and alert.
21. A sparrow is very alert in its movements.
22. His voice was alert, not the least bit sleepy.
23. We all have to stay alert.
24. We must be alert to the possibility of danger.
25. Climbers need to be alert to possible dangers.
26. Her whole bearing was alert.
27. All our border points are on full alert.
28. I was hoping he'd alert the police.
29. The all clear was sounded about 10 minutes after the alert was given.
30. Every police car and foot patrol in the area is on full alert.