Source : Webster's Revised Unabridged Dictionary (1913)

Rumination \Ru`mi*na"tion\, n. [L. ruminatio: cf. F.
   rumination.]
   1. The act or process of ruminating, or chewing the cud; the
      habit of chewing the cud.

            Rumination is given to animals to enable them at
            once to lay up a great store of food, and afterward
            to chew it.                           --Arbuthnot.

   2. The state of being disposed to ruminate or ponder;
      deliberate meditation or reflection.

            Retiring full of rumination sad.      --Thomson.

   3. (Physiol.) The regurgitation of food from the stomach
      after it has been swallowed, -- occasionally observed as a
      morbid phenomenon in man.

Source : WordNet®

rumination
     n 1: a calm lengthy intent consideration [syn: {contemplation}, {reflection},
           {reflexion}, {musing}, {thoughtfulness}]
     2: (of ruminants) chewing (the cud); "ruminants have remarkable
        powers of rumination"
     3: regurgitation of small amounts of food; seen in some infants
        after feeding