It is an adjective and its first usage dates back to 15th century. It has originated from Lain word vigilant-, vigilans, which means to keep watch.
Meanings of Vigilant
1) Someone alert to watch out for any kind of danger
2) Someone awake or alert
Master’s tip to learn vigilant:
Vigilant can be learnt with the help of a police department that is active in every state of the country .i.e. department of vigilance, as vigilance has also been derived from the word vigilant. And the function of the vigilance department is also to be watchful for dangers.
Sentence examples for Vigilant:
1) He is petrified for his daughter’s safety, so he stays ever vigilant. (Adjective)
2) His agile nature of the mind complements his vigilant outlook in life. (Noun)
3) He vigilantly overturned the military’s attempt to carry put genocide. (Adverb)