was·sail 
(wŏsəl, wŏ-sāl)
(wŏsəl, wŏ-sāl)n.
1.
a. A salutation or toast given in drinking someone's health or as an expression of goodwill at a festivity.
b. The drink used in such toasting, commonly ale or wine spiced with roasted apples and sugar.
2. A festivity characterized by much drinking.
v. was·sailed, was·sail·ing, was·sails
v.tr.
To drink to the health of; toast.
v.intr.
To engage in or drink a wassail.
[Middle English, contraction of wæshæil, be healthy, from Old Norse ves heill : ves, imperative sing. of vera, to be; see wes-1 in the Appendix of Indo-European roots + heill, healthy; see kailo- in the Appendix of Indo-European roots.]
wassail·er n.
Word History: Wassail is an English holiday drink consisting of spiced mulled wine, ale, or some other fermented beverage such as hard cider or mead. The word is also used as a verb: to drink someone's health, especially in the course of traveling around one's neighborhood, singing songs at neighbors' houses and receiving food and drink in return, is to wassail—as in the traditional carol "Here We Come A-Wassailing."¶Both the noun wassail and its associated verb come from one of the most popular expressions used in medieval England in toasting someone's health. The Middle English toast Wæshæil! comes from the Old Norse salutation Ves heill! which had been brought to Britain by the invading Danes in the 9th Century AD. The Anglo-Saxons, for their part, had a corresponding salutation, Wes þū hāl! which they used as a general greeting—variations of it can be found in Beowulf (Wæs þū, Hroðgar, hāl! says the young hero when he meets King Hrothgar) and in the West Saxon Gospels (at the Annunciation, the angel Gabriel greets Mary with Hāl wes þū!).¶These greetings and toasts literally mean "Be healthy!"—a sentiment that survives in the Modern English toast To your health! and in many toasts in other languages, such as the Spanish Salud! and the French Santé! which both simply mean "health." The Old English hāl, incidentally, means not only "healthy" (it is the origin of Modern English hale) but also "undamaged, entire" (it is also the origin of the word whole).