Why is it called Halloween?

The All Saints Day celebration was also called All-hallows or All-hallowmas (from Middle English Alholowmesse meaning All Saints' Day) and the night before it, the traditional night of Samhain in the Celtic religion, began to be called All-hallows Eve and, eventually, Halloween.

The All Saints Day celebration was also called All-hollows or All-hallowmas (from Middle English alholowmesse meaning All Saints Day) and the night before it, the traditional night of Samhain in the Celtic religion, began to be called All-hallows Eve and, eventually Halloween.