Ash Wednesday

Từ điển Oxford Advanced Learner 8th

ˌAsh ˈWednesday BrE NAmE noun uncountable, countable
the first day of Lent
see also ↑Shrove Tuesday

Word Origin:
[Ash Wednesday] from the custom of marking the foreheads of penitents with ashes on that day.

Culture:
Traditionally, ↑Roman Catholics go to church on Ash Wednesday and their foreheads are marked with ashes as a sign that human bodies become dust. In the US this tradition is still widely followed. The ashes are not washed off but left to go away on their own. It is polite not to make a comment on the mark on a person’s forehead.