The word Halloween or Hallowe’en dates to about 1745 and is of Christian origin. The word “Halloween” means “hallowed evening” or “holy evening”. It comes from a Scottish term for All Hallows’ Eve (the evening before All Hallows’ Day). In Scots, the word “eve” is even, and this is contracted to e’en or een. Over time, (All) Hallow(s) E(v)en evolved into Halloween. Although the phrase “All Hallows'” is found in Old English (ealra hālgena mæssedæg, mass-day of all saints), “All Hallows’ Eve” is itself not seen until 1556. via Wikipedia
the night of October 31, the eve of All Saints’ Day, commonly celebrated by children who dress in costume and solicit candy or other treats door-to-door.