The first week day after Christmas, a legal holiday on which Christmas boxes are given to postmen, errand boys, employees, etc. The night of this day is boxing night.

n. 1. A holiday which falls on the day after Christmas (the Feast of St. Stephen). In earlier years the wealthy would put leftover Christmas food in boxes for their servants or the poor.

first weekday after Christmas

December 26 (a public holiday in Great Britain)

Boxing Day is a public holiday celebrated in the United Kingdom and most other Commonwealth countries on December 26, the day after Christmas Day. American Heritage Dictionary, Fourth Edition - 'Boxing Day'Oxford English. People, especially woman, had to stip just to get in the party area.