The Collaborative International Dictionary of English v.0.48:

Mull \Mull\, v. t. [imp. & p. p. Mulled (m[u^]ld); p. pr. &
   vb. n. Mulling.] [From mulled, for mold, taken as a p. p.;
   OE. mold-ale funeral ale or banquet. See Mold soil.]
   1. To heat, sweeten, and enrich with spices; as, to mull
      wine.
      [1913 Webster]

            New cider, mulled with ginger warm.   --Gay.
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   2. To dispirit or deaden; to dull or blunt. --Shak.
      [1913 Webster] Mulla