Source : Webster's Revised Unabridged Dictionary (1913)

Pestle \Pes"tle\, n. [OE. pestel, OF. pestel, LL. pestellum, L.
   pistillum, pistillus, a pounder, pestle, fr. pisere, pinsere,
   to pound, crush, akin to Gr. ?, Skr. pish. Cf. {Pistil}.]
   1. An implement for pounding and breaking or braying
      substances in a mortar.

   2. A constable's or bailiff's staff; -- so called from its
      shape. [Obs.] --Chapman.

   3. The leg and leg bone of an animal, especially of a pig;
      as, a pestle of pork.

Pestle \Pes"tle\, v. t. & i. [imp. & p. p. {Pestled}; p. pr. &
   vb. n. {Pestling}.]
   To pound, pulverize, bray, or mix with a pestle, or as with a
   pestle; to use a pestle.

Source : WordNet®

pestle
     n 1: machine consisting of a heavy bar that moves vertically for
          pounding or crushing ores [syn: {stamp}]
     2: a heavy tool of stone or iron (usually with a flat base and
        a handle) that is used to grind and mix material (as grain
        or drugs or pigments) against a slab of stone [syn: {muller},
         {pounder}]
     3: a club-shaped hand tool for grinding and mixing substances
        in a mortar
     v : grind or pulverize in a pestle