air alert

Từ điển WordNet v3.1 - WordNet Dictionary

noun

1. the time period during which military and civilian agencies are prepared for an enemy air attack
• Hypernyms:
time period, period of time, period
2. the condition in which combat aircraft are airborne and ready for an operation
- aircraft in the Mideast are on air alert
• Hypernyms:
alert, qui vive
3. the warning signal that begins a period of preparation for an enemy air attack
• Hypernyms:
alarm, alert, warning signal, alarum