Synonyms and related words :
Argus-eyed, advertent, agog, alert, all eyes, assiduous, attentive, aux aguets, aware, careful, concentrated, conscious, custodial, diligent, eagle-eyed, earnest, finical, finicking, finicky, guarded, hawk-eyed, heedful, intense, intent, intentive, keen-eyed, lidless, listening, meticulous, mindful, nice, niggling, observant, observing, on guard, on the ball, on the job, on the lookout, on the watch, open-eared, open-eyed, openmouthed, prudent, regardful, sharp-eyed, sleepless, vigilant, wary, watchful, with open eyes,