1. alert, qui vive

condition of heightened watchfulness or preparation for action

Example Sentences:
'bombers were put on alert during the crisis'

• qui vive

2. alert, alerting

a warning serves to make you more alert to danger

• alerting

3. alarm, alarum, alert, warning signal

an automatic signal (usually a sound) warning of danger

• alarm
• alarum
• warning signal

4. alarm, alert

warn or arouse to a sense of danger or call to a state of preparedness

Example Sentences:
'The empty house alarmed him'
'We alerted the new neighbors to the high rate of burglaries'

• alarm

5. alert, watchful

engaged in or accustomed to close observation

Example Sentences:
'caught by a couple of alert cops'
'alert enough to spot the opportunity when it came'
'constantly alert and vigilant, like a sentinel on duty'

• watchful

• argus-eyed
• open-eyed
• vigilant
• wakeful
• fly
• heads-up
• wide-awake
• lidless
• sleepless

6. alert, brisk, lively, merry, rattling, snappy, spanking, zippy

quick and energetic

Example Sentences:
'a brisk walk in the park'
'a lively gait'
'a merry chase'
'traveling at a rattling rate'
'a snappy pace'
'a spanking breeze'

• brisk
• lively
• merry
• rattling
• snappy
• spanking
• zippy

7. alert, alive, awake

mentally perceptive and responsive

Example Sentences:
'an alert mind'
'alert to the problems'
'alive to what is going on'
'awake to the dangers of her situation'
'was now awake to the reality of his predicament'

• alive
• awake

• aware
• cognisant
• cognizant