| canny(adjective, cautious, suspicious, watchful) |
| on the ball(expression, adjective, idiom, keen, sharp) |
| on your guard(expression, adjective, idiom, alert, attentive) |
| open-eyed(adjective, keen, anxious, alert, careful) |
| aware(adjective, keen, alert, careful, attentive) |
| chary(adjective, alert, careful, considerate, cautious) |
| custodial(adjective, defensive, overprotective, preservative) |
| defensive(adjective, adverb, alert, careful, wary) |
| discreet(cautious, suspicious, watchful) |
| eagle-eyed |
| keen-eyed |
| leery(adjective, cautious, suspicious, watchful) |
| noncommittal |
| on the alert(expression, adjective, idiom, alert, careful) |
| on the job(expression, adjective, idiom, keen, sharp) |
| on the qui vive(expression, adjective, idiom, keen, sharp) |
| ready(adjective, set, sharp, bright, lively) |
| regardful |
| sharp-eyed |
| sleepless(keen, anxious, alert, careful, disturbed) |