Vigil

Webster's Dictionary

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

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

(3): ( 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.

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

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

Charles Buck Theological Dictionary

The eve or day before any solemn feast, because then Christians were want to watch, fast and pray in their churches.