The word turns up in English in 1546, and it did not mean a holiday. It meant that the sweetness of a new marriage waned like the Moon.

The earliest uses are cynical: the honey is at the full, and from here it goes down. The travel sense arrives three centuries later, when couples started taking bridal tours. There is a persistent story about a month of mead in Norse or Babylonian custom; nobody has found a source for it earlier than the twentieth century.