halloween or Hallowe’en (a contraction of “All Hallows’ evening”),^[5] also known as Allhalloween,^[6] All Hallows’ Eve,^[7] or All Saints’ Eve,^[8] is a celebration observed in many countries on 31 October, the eve of the Western Christian feast of All Hallows’ Day. It begins the observance of Allhallowtide,^[9] the time in the liturgical year dedicated to remembering the dead, including saints (hallows), martyrs, and all the faithful departed.^[10][11]

One theory holds that many Halloween traditions may have been influenced by ancient Celtic harvest festivals, particularly the Gaelic festival Samhain, which may have had pagan roots;^{[12][13][14][15]} some scholars hold that Samhain may have been Christianized as All Hallow’s Day, along with its eve, by the early Church.^[16] Other academics believe, however, that Halloween began solely as a Christian holiday, being the vigil of All Hallow’s Day.^{[17][18][19][20]}