VIGILANT

vigilant, open-eyed, argus-eyed, wakeful

(adjective) carefully observant or attentive; on the lookout for possible danger; “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”

Source: WordNet® 3.1

Etymology

Adjective

vigilant (comparative more vigilant, superlative most vigilant)

Watchful, especially for danger or disorder; alert; wary

Synonyms

• (watchful): alert, aware, observant, on the qui vive, wakesome, wary, watchful

Source: Wiktionary

Vig"i*lant, a. Etym: [L. vigilans, -antis, p. pr. of vigilare to watch, fr. vigil awake: cf. F. vigilant. See Vigil.]

Definition: Attentive to discover and avoid danger, or to provide for safety; wakeful; watchful; circumspect; wary. "Be sober, be vigilant." 1 Pet. v. 8. Sirs, take your places, and be vigilant. Shak.

Source: Webster’s Unabridged Dictionary 1913 Edition