Festum omnium sanctorum
The festival of All Saints, also sometimes known as All Hallows or Hallowmas (“hallows” meaning “saints,” and “mas” meaning “Mass“), is a feast celebrated in their honor. Halloween is the day proceeding it, and is so named because it is” The Eve of All Hallows”. All Saints is also a Christian formula invoking all the faithful saints and martyrs, known or unknown. The Western Christian holiday (called Festum omnium sanctorum in Latin) falls on November 1, followed by All Souls’ Day on November 2, and is a Holy Day of Obligation in the Latin Rite Roman Catholic Church, with a vigil and an octave. Among the Eastern Orthodox and Eastern Rite Catholics, All Saints follows the earlier tradition kept by the whole Church of keeping the feast on the first Sunday after Pentecost and as such marks the close of the Easter season.