digestion

Etymology

From Old French digestion. Partly displaced native Old English melting (“melting, digestion”).

noun

1. The process, in the gastrointestinal tract, by which food is converted into substances that can be utilized by the body.
   In the dead state all is apparently without motion. No agent within indicates design, intelligence, or foresight: there is no respiration; no digestion, circulation, or nutrition; […] 1822, John Barclay, chapter I, in An Inquiry Into the Opinions, Ancient and Modern, Concerning Life and Organization, Edinburgh, London: Bell & Bradfute; Waugh & Innes; G. & W. B. Whittaker, section I, page 2
   Mostly, the microbiome is beneficial. It helps with digestion and enables people to extract a lot more calories from their food than would otherwise be possible. Research over the past few years, however, has implicated it in diseases from atherosclerosis to asthma to autism. 2013-06-29, “A punch in the gut”, in The Economist, volume 407, number 8842, pages 72–3
2. The result of this process.
3. The ability to use this process.
4. The processing of decay in organic matter assisted by microorganisms.
5. The assimilation and understanding of ideas.
6. (medicine, archaic) Generation of pus; suppuration.
7. (chemistry) Dissolution of a sample into a solution by means of adding acid and heat.