[dih-jes-chuhn, dahy-]
the process in the alimentary canal by which food is broken up physically, as by the action of the teeth, and chemically, as by the action of enzymes, and converted into a substance suitable for absorption and assimilation into the body.
the function or power of digesting food: My digestion is bad.
the act of digesting or the state of being digested.

1350–1400; Middle English digestioun < Anglo-French, Middle French < Latin dīgestiōn- (stem of dīgestiō), equivalent to dīgest(us) (see digest) + -iōn- -ion

digestional, adjective
nondigestion, noun
redigestion, noun
self-digestion, noun
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
digestion (dɪˈdʒɛstʃən, daɪ-)
1.  the act or process in living organisms of breaking down ingested food material into easily absorbed and assimilated substances by the action of enzymes and other agentsRelated: peptic
2.  mental assimilation, esp of ideas
3.  bacteriol the decomposition of sewage by the action of bacteria
4.  chem the treatment of material with heat, solvents, chemicals, etc, to cause softening or decomposition
Related: peptic
[C14: from Old French, from Latin digestiō a dissolving, digestion]

Collins English Dictionary - Complete & Unabridged 10th Edition
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Word Origin & History

late 14c., from Fr. digestion (13c.), from L. digestionem, noun of action from digerere (see digest (n.)).
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

digestion di·ges·tion (dī-jěs'chən, dĭ-)
The process by which food is converted into substances that can be absorbed and assimilated by the body, especially that accomplished in the alimentary canal by the mechanical and enzymatic breakdown of foods into simpler chemical compounds.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
digestion   (dī-jěs'chən)  Pronunciation Key 

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  1. The process by which food is broken down into simple chemical compounds that can be absorbed and used as nutrients or eliminated by the body. In most animals, nutrients are obtained from food by the action of digestive enzymes. In humans and other higher vertebrates, digestion takes place mainly in the small intestine. In protists and some invertebrates, digestion occurs by phagocytosis.

  2. The decomposition of organic material, such as sewage, by bacteria.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Cultural Dictionary

digestion definition

The breaking down of food, which is made up of complex organic molecules, into smaller molecules that the body can absorb and use for maintenance and growth.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Example sentences
As the stomach releases food into the intestines, the gallbladder begins to
  squeeze out bile to help with fat digestion.
It is always craving new and more tasty morsels-which may not be the best, or
  truest, things for anyone's digestion.
Human guts are full of bugs that help digestion and also stop their
  disease-causing counterparts from invading.
Those are parts some nudibranchs have for breathing and digestion.
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