Source : Webster's Revised Unabridged Dictionary (1913)

Cud \Cud\ (k[u^]d), n. [AS. cudu, cwudu,cwidu,cweodo, of
   uncertain origin; cf, G. k["o]der bait, Icel. kvi[eth]r womb,
   Goth. qi[thorn]us. Cf. {Quid}.]
   1. That portion of food which is brought up into the mouth by
      ruminating animals from their first stomach, to be chewed
      a second time.

            Whatsoever parteth the hoof, and is cloven-footed,
            and cheweth the cud, among the beasts, that shall ye
            eat.                                  --Levit. xi. 3

   2. A portion of tobacco held in the mouth and chewed; a quid.
      [Low]

   3. The first stomach of ruminating beasts. --Crabb.

   {To chew the cud}, to ruminate; to meditate; used with of;
      as, to chew the cud of bitter memories.

            Chewed the thrice turned cud of wrath. --Tennyson.

Source : WordNet®

cud
     n 1: food of a ruminant regurgitated to be chewed again [syn: {rechewed
          food}]
     2: a wad of something chewable as tobacco [syn: {chew}, {chaw},
         {quid}, {plug}, {wad}]