Available Definitions:
1) n. - An ancient expression of good wishes on a festive occasion, especially in drinking to some one.
2) n. - An occasion on which such good wishes are expressed in drinking; a drinking bout; a carouse.
3) n. - The liquor used for a wassail; esp., a beverage formerly much used in England at Christmas and other festivals, made of ale (or wine) flavored with spices, sugar, toast, roasted apples, etc.; -- called also lamb's wool.
4) n. - A festive or drinking song or glee.
5) a. - Of or pertaining to wassail, or to a wassail; convivial; as, a wassail bowl.
6) v. i. - To hold a wassail; to carouse.