(DAY BEFORE) [noun] [U] - the period or day before an important event, or (old use) an eveningMr Hurd was speaking to Arab journalists in London on the eve of his visit to Jordan and Saudi Arabia.Christmas Eve is on December 24th.Are you doing anything exciting on New Year's Eve (= the last day of the year)?
EVE
Meaning of EVE in English
Cambridge English vocab. Кембриджский английский словарь. 2012