Dictionary.net

A festive occasion or meeting where drinking and pledging of healths are indulged in; festivities; a drinking bout; a carouse; the liquor used on such occasions, especially about Christmas or the New Year. It consists of ale (sometimes wine) sweetened with sugar, and flavored with nut meg, cinnamon, cloves, roasted apples, etc.; a merry drinking song; “Have you done your wassail? Tis a handsome drowsy ditty, I assure you.”-Beau. & Fl.