Today Halloween is primarily marked by putting on a disguise and asking for candy, but Halloween has its roots in at least two Medieval celebrations: the Celtic festival of Samhain and the Christian holiday All Saint’s Day. The spooky festival's name, however, comes from only one. Samhain is Gaelic for "summer's end," and marks what has loosely been labeled the "Celtic New Year," the end of the “lighter half” of the year and the beginning of the “darker half." One of the four fire festivals of the year, it was celebrated on November 1 when, it was believed, the dead arose for one night. Sound familiar? The other celebration, All Saint’s Day, honors all of the Catholic saints. The Roman Catholic Church refers to it as the "Solemnity of All Saints." Though this celebration does not bear a close resemblance to the festivities of Halloween, it did give the holiday its name. The word Halloween is a direct derivation of All Saints’ Day.
All Hallows in Old English means “the feast of the saints.” Halloween, first attested in the 18th century, is a Scottish variant of All-Hallows-Even. The Even meant evening. The spelling of the word was once Hallowe’en, in which the “v” was elided. The current spelling wasn’t widely adopted until the 20th century.