形容詞 vigilant:

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

1. One must be ever vigilant.
   每個(gè)人必須隨時(shí)提高警覺(jué)。
2. The dog kept a vigilant guard over the house.
   這只狗警醒地守護(hù)著這所房屋。
3. I am afraid under the vigilant eyes of the examiner.
   在檢察員警惕的目光下，我害怕了。
4. The police said that the public should be vigilant.
   警方說(shuō)公眾應(yīng)保持警惕。

vig.i.lant

adj.（形容詞）
On the alert; watchful.See Synonyms at aware
警惕的；警覺(jué)的參見(jiàn) aware

來(lái)源：
Middle English
中古英語(yǔ)
from Old French
源自 古法語(yǔ)
from Latin vigil3ns vigilant- [present participle of] vigil3re [to be watchful] * see vigilante
源自 拉丁語(yǔ) vigil3ns vigilant- [] vigil3re的現(xiàn)在分詞 [保持警戒的] *參見(jiàn) vigilante

【引伸】
vig.ilantly
adv.（副詞）