means The state of being alert and watchful, especially for danger or trouble before it arrives.

from From the Latin 'vigilare,' to keep awake or stay watchful, which sprang from 'vigil' — one who stays up through the night, alert while others sleep. The same root keeps watch in 'vigil' itself and in 'vigilante,' and it's a distant cousin of 'vegetable' and 'vigor,' all tracing back to a Proto-Indo-European root meaning lively or full of vital force. To be vigilant, in the deepest sense, is simply to be wide awake.