Boxing Day 
noun British
A public holiday celebrated on the first day (strictly, the first weekday) after Christmas Day.It was expected to be even busier today - the official Boxing Day bank holiday....
- When I was a child Boxing Day was my favourite Day of the Christmas Holidays.
- Before Boxing Day last year, the coastal towns and villages of Sri Lanka had vibrant communities.
Origin
Mid 19th century: from the custom of giving tradespeople a Christmas box on this day.