Ash Wednesday 大齋首日

大齋首日（又名聖灰星期三、聖灰日、灰日，英語：Ash Wednesday），是基督宗教的教會年曆節期大齋期（四旬期）之始。

當天教會會舉行塗灰禮，要把去年棕枝主日祝聖過的棕枝燒成灰，在禮儀中塗在教友的額頭上，作為悔改的象征。

大齋首日是根據複活節的日期前四十天（不計算主日），因此每年的大齋首日的日期都不同。最早可以是二月四日，最遲是三月十日。

Ash Wednesday, in the calendar of Western Christianity, is the first day of Lent and occurs 46 days before Easter. It is a moveable fast, falling on a different date each year because it is dependent on the date of Easter. It can occur as early as February 4 or as late as March 10.

According to the canonical gospels of Matthew, Mark and Luke; Jesus spent 40 days fasting in the desert before the beginning of his public ministry, during which he endured temptation by Satan.^[2][3] Ash Wednesday marks the beginning of this 40-day liturgical period of prayer and fasting.

Ash Wednesday derives its name from the practice of placing ashes on the foreheads of adherents as a sign of mourning and repentance to God. The ashes used are typically gathered after the palms from the previous year's Palm Sunday are burned.^[4]

This practice is common in much of Christendom, being celebrated by Catholics, Anglicans, Lutherans, Methodists, Presbyterians, and some Baptist denominations.^[