Synonyms and related words :
Argus-eyed, all ears, all eyes, aux aguets, cat-eyed, clear-eyed, clear-sighted, custodial, eagle-eyed, eye-minded, farseeing, farsighted, ferret-eyed, guarded, keen-eyed, lidless, observant, on guard, on the lookout, on the watch, open-eyed, prudent, sharp-eyed, sharp-sighted, sleepless, telescopic, vigilant, wary, watchful, with open eyes