rumination

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The act of thinking about something in a sustained fashion.
• noun The act or process of chewing cud.

from The Century Dictionary.

• noun The act or process of ruminating, or chewing the cud.
• noun The act of ruminating or meditating; a musing or continued thinking on a subject; meditation or reflection.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act or process of ruminating, or chewing the cud; the habit of chewing the cud.
• noun The state of being disposed to ruminate or ponder; deliberate meditation or reflection.
• noun (Physiol.) The regurgitation of food from the stomach after it has been swallowed, -- occasionally observed as a morbid phenomenon in man.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The act of ruminating; i.e. chewing cud and other ruminants.
• noun figuratively Deep thought or consideration.
• noun psychology Negative cyclic thinking; persistent and recurrent worrying or brooding.
• noun pathology An eating disorder characterized by repetitive regurgitation of small amounts of food from the stomach.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (of ruminants) chewing (the cud)
• noun a calm, lengthy, intent consideration
• noun regurgitation of small amounts of food; seen in some infants after feeding