Etymology

Holiday

Holiday is a contraction of holy and day. Holiday originally refered only to special religious days. In modern use, it means any special day of rest, as opposed to normal days off work or school.

Vacation

In the United Kingdom, vacation once specifically referred to the long summer break taken by the law courts and, later, universities—a custom introduced by William the Conqueror from Normandy where it facilitated the grape harvest. The French term is similar to American English: "Les Vacances." In the past, many upper-class families moved to a summer home for part of the year, leaving their usual family home vacant.