Synonyms for vigilant:
Other synonyms and related words:
conscious, sharp-sighted, light, wide-awake, circumspect, lynx-eyed, expectant, alive, hawk-eyed, undivided, wakeful, quick-sighted, jealous, keen-sighted, sleepless, waking, open-eyed, wary, awake, tenty, on the alert, argus-eyed.
careful, watchful (adjective)
guarded, mindful, regardful, finical, cautious, sharp-eyed, thorough, watchful, attentive, provident, strict, ready, diligent, prudent, observant, meticulous, careful, scrupulous, thoughtful, heedful, alert, fastidious, fussy, prepared, conscientious, responsible, precise, particular, exacting.
Sense 3 (noun)