The evening or the day before a particular day or event, esp. a holy day or religious festival; = eve, n.2 2a. Now rare except in certain fixed…
(After holiday, n. 1, holy-day, n.) A night that is kept holy, as the eve of a festival. Obsolete.
The evening, and hence the day, that immediately precedes a particular day or event, esp. a holy day or religious festival. Also figurative.
The eve of a festival, or of the Passion.