vigilant

形容词 vigilant:

1. carefully observant or attentive; on the lookout for possible danger
   同义词：argus-eyed, open-eyed, wakeful, watchful

1. One must be ever vigilant.
   每个人必须随时提高警觉。
2. The dog kept a vigilant guard over the house.
   这只狗警醒地守护着这所房屋。
3. I am afraid under the vigilant eyes of the examiner.
   在检察员警惕的目光下，我害怕了。
4. The police said that the public should be vigilant.
   警方说公众应保持警惕。

vig.i.lant

adj.（形容词）
On the alert; watchful.See Synonyms at aware
警惕的；警觉的参见 aware

来源：
Middle English
中古英语
from Old French
源自 古法语
from Latin vigil3ns vigilant- [present participle of] vigil3re [to be watchful] * see vigilante
源自 拉丁语 vigil3ns vigilant- [] vigil3re的现在分词 [保持警戒的] *参见 vigilante

【引伸】
vig.ilantly
adv.（副词）