wassail

The story

1. Old Norse · derived fromves heill“be healthy!”
2. Middle English · inherited fromwassail
3. English todaywassail

From Middle English wassail, from Old Norse ves heill (“be healthy!”), from the imperative of vesa (“to be”) + heill (“healthy”). The earliest documented use of the term is from the first part of the 12th century CE, in Geoffroy of Monmouth's Historia Regum Britanniae (see page's citations).