Synonyms of vigilant

Adjective

1. argus-eyed, open-eyed, vigilant, wakeful, alert (vs. unalert), watchful

usage: carefully observant or attentive; on the lookout for possible danger; "a policy of open-eyed awareness"; "the vigilant eye of the town watch"; "there was a watchful dignity in the room"; "a watchful parent with a toddler in tow"

Definition and meaning of vigilant (Dictionary)