The Collaborative International Dictionary of English v.0.48:

Wassail \Was"sail\, a.
   Of or pertaining to wassail, or to a wassail; convivial; as,
   a wassail bowl. "Awassail candle, my lord, all tallow."
   --Shak.
   [1913 Webster]

   Wassail bowl, a bowl in which wassail was mixed, and placed
      upon the table. "Spiced wassail bowl." --J. Fletcher.
      "When the cloth was removed, the butler brought in a huge
      silver vessel . . . Its appearance was hailed with
      acclamation, being the wassail bowl so renowned in
      Christmas festivity." --W. Irving.

   Wassail cup, a cup from which wassail was drunk.
      [1913 Webster]