Vigil

n. period of wakefulness during the night (particularly for the purpose of watching or guarding); time of prayer on the eve of a religious holiday

This article is about the period of sleeplessness. For all other usages, see Vigil (disambiguation). A vigil (from the Latin vigilia, 'wakefulness') is a period of sleeplessness, an occasion for devotional watching or observance.It can also be the eve of a religious festival observed by staying awake as a devotional exercise or ritual devotions observed on the eve of a holy day, such as the Easter Vigil held on Holy Saturday. In the Eastern Orthodox Church an All-Night Vigil is held on the eves of Sundays and all major feasts during the liturgical year.
See more at Wikipedia.org...

Noun
1. a period of sleeplessness
(hypernym) wakefulness
2. a devotional watch (especially on the eve of a religious festival)
(synonym) watch
(hypernym) rite, religious rite
(hyponym) wake, viewing
(classification) religion, faith, religious belief
3. a purposeful surveillance to guard or observe
(synonym) watch
(hypernym) surveillance
(hyponym) listening watch, continuous receiver watch

(v. i.)
Originally, the watch kept on the night before a feast.
  

(v. i.)
Later, the day and the night preceding a feast.
  

(v. i.)
Hence, devotional watching; waking for prayer, or other religious exercises.
  

(v. i.)
Abstinence from sleep, whether at a time when sleep is customary or not; the act of keeping awake, or the state of being awake, or the state of being awake; sleeplessness; wakefulness; watch.
  

(v. i.)
A religious service performed in the evening preceding a feast.
  

The knight ’s watch the night before his elevation to knighthood , the accolade , frequently conducted upon the altar at a church . There is little mention of the practice before the late 15th century, yet it has become an iconographic part of the knightly image.
Modern knights in the SCA hold their vigils all night, from ‘dusk till dawn’, often attended by other knights of high renown , who speak to the candidate about what it means to be a knight.