vigilant

paying close attention usually for the purpose of anticipating approaching danger or opportunity the night watchman, who was usually vigilant, apparently dozed off and didn't notice the vandals sneaking in Synonyms Argus-eyed, attentive, awake, observant, open-eyed, tenty (also tentie) [Scottish], alert, watchful, wide-awakeRelated Words alive, aware, conscious, sensitive; cognizant, heedful, keen, mindful, observing, regardful, sharp, sharp-eyed; hyperalert, hypervigilant, sleepless, wakeful; careful, cautious, chary, wary; prepared, readyNear Antonyms absent, absentminded, absorbed, abstracted, daydreaming, dazed, distracted, dreaming, dreamy, engrossed, faraway, insensible, oblivious, preoccupied; sleeping, unaware, unconscious, unknowing, unwitting; careless, heedless, inattentive, unheeding, unmindful, unthinking, unwary; unprepared, unreadyAntonyms asleep