Dame Maggie Smith in Season One of Downton Abbey |
According to the Oxford English Dictionary (which from here on out I shall refer to as the OED simply because it is quite overwhelming to read such an striking title repeatedly), the word weekend, which literally meant end of week, has been documented to be around since 1638. However, OED documents that it got its start in print around the 1910s, the era of Downton Abbey and often referred to a holiday (American term: vacation) at the end of the work week. The term did not make it into dictionaries until 1926 though it was being tossed about before that date.
In 1972, the OED states that apparently Monty Python turned the term into a euphemism. I won't tell you any more here. If you must know, go do some research. With that knowledge in mind, I am sure the British couldn't keep a straight face when the Dowager Countess asked her simple question.
week-end, n.
Third edition, October 2011; online version December 2011. <http://www.oed.com/view/Entry/226788>; accessed 05 February 2012. An entry for this word was first included in New English Dictionary, 1926.