Halloween
When
Body

Halloween, contraction of All Hallows’ Eve, a holiday observed on October 31, the evening before All Saints’ (or All Hallows’) Day. The celebration marks the day before the Western Christian feast of All Saints and initiates the season of Allhallowtide, which lasts three days and concludes with All Souls’ Day. In much of Europe and most of North America, observance of Halloween is largely nonreligious.

- Britannica.com