also: イヴ
noun
eve; night before
Primarily refers to Christmas Eve (クリスマスイブ), but can be used for the eve of other events. A loanword from English 'eve'.
クリスマスイブに家族で集まる。
We gather with family on Christmas Eve.
大晦日は新年のイブとも言える。
New Year's Eve can be called the eve of the new year.