/,hæləʊ'i:n; ,hælo`in/
n
31 October, the eve of All Saints' Day 万圣节前夕（10月31日）.

n[U]
[Date: 1700-1800; Origin: All Hallow Even 'All Saints' Eve'; HALLOWED]
the night of October 31st, which is now celebrated by children, who dress in costumes and go from house to house asking for sweets, especially in the US and Canada. In the past, people believed the souls of dead people appeared on Halloween.