Source : Webster's Revised Unabridged Dictionary (1913)

Mull \Mull\, v. t. [OE. mullen. See 2d {Muller}.]
   To powder; to pulverize. [Prov. Eng.]

Mull \Mull\, v. i.
   To work (over) mentally; to cogitate; to ruminate; -- usually
   with over; as, to mull over a thought or a problem. [Colloq.
   U.S.]

Mull \Mull\, n.
   An inferior kind of madder prepared from the smaller roots or
   the peelings and refuse of the larger.

Mull \Mull\, v. t. [imp. & p. p. {Mulled}; 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.

            New cider, mulled with ginger warm.   --Gay.

   2. To dispirit or deaden; to dull or blunt. --Shak.

Mull \Mull\ (m[u^]l), n. [Perh. contr. fr. mossul. See
   {Muslin}.]
   A thin, soft kind of muslin.

Mull \Mull\, n. [Icel. m[=u]li a snout, muzzle, projecting crag;
   or cf. Ir. & Gael. meall a heap of earth, a mound, a hill or
   eminence, W. moel. Cf. {Mouth}.]
   1. A promontory; as, the Mull of Cantyre. [Scot.]

   2. A snuffbox made of the small end of a horn.

Mull \Mull\, n. [Prob. akin to mold. [root]108. See {Mold}.]
   Dirt; rubbish. [Obs.] --Gower.

Source : WordNet®

mull
     v 1: reflect deeply on a subject; "I mulled over the events of
          the afternoon"; "philosophers have speculated on the
          question of God for thousands of years"; "The scientist
          must stop to observe and start to excogitate" [syn: {chew
          over}, {think over}, {meditate}, {ponder}, {excogitate},
           {contemplate}, {muse}, {reflect}, {mull over}, {ruminate},
           {speculate}]
     2: heat with sugar and spices to make a hot drink; "mulled
        cider"

mull
     n 1: a term used in Scottish names of promontories; "the Mull of
          Kintyre"
     2: an island in western Scotland in the Inner Hebrides