Vigilant 是一个容易与常见单词 diligent （勤奋的；细致而坚持不懈的）相混淆的单词。该词源自拉丁语vigilare（观察，保持清醒，不睡觉，保持警惕），15世纪末经法语vigilant或者直接由拉丁语vigilantem（警惕的、焦虑的、小心的）进入英语，也是用来表示“警觉的、警惕的、警戒的”，主要指为了避免可能发生或存在的危险、困难、非法活动等而保持警惕的，常含有敏锐和勇敢的意味，

比如：

keep a vigilant eye upon对……保持警戒

be as vigilant as a cat像猫一般警觉

Be vigilant against the danger of enemy agents infiltrating the government and boring from within.要警惕敌特渗入政府内部进行暗中破坏。

We must be highly vigilant against external attempts to foment a new Cold War or camp-based confrontation in our region. We must resolutely reject any interference in our internal affairs and the instigation of "color revolutions" by any country under whatever pretext. The future of our development must be held firmly in our own hands.权威用例要高度警惕外部势力在本地区煽动“新冷战”、制造阵营对抗，坚决反对任何国家以任何理由干涉内政、策动“颜色革命”，把本国发展进步的前途命运牢牢掌握在自己手中。

出自习主席在上海合作组织成员国元首理事会第二十三次会议上的讲话（双语全文）

wary: feeling or showing caution about possible dangers or problems watchful: watching or observing someone or something closely; alert and vigilant observant: quick to notice things同近义词