Main entry: vigilant, wakeful, open-eyed, argus-eyed
Definition: carefully observant or attentive; on the lookout for possible danger
Usage: 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
Main entry: sharp-eyed, sharp-sighted, argus-eyed, hawk-eyed, lynx-eyed, keen-sighted, quick-sighted
Definition: having very keen vision
Usage: quick-sighted as a cat