fermentation

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

• noun Any of a group of chemical reactions induced by microorganisms or enzymes that split complex organic compounds into relatively simple substances, especially the anaerobic conversion of sugar to carbon dioxide and alcohol by yeast.
• noun Unrest; agitation.

from The Century Dictionary.

• noun A gentle boiling or ebullition.
• noun A decomposition produced in an organic substance by the physiological action of a living organism or by certain unorganized agents. See ferment.
• noun Figuratively, the state of being in high activity or commotion; agitation; excitement, as of the intellect or feelings, a society, etc.
• noun See the adjectives.
• noun Synonyms See ebullition.

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

• noun (Physiol. Chem.) The process of undergoing an effervescent change, as by the action of yeast
• noun A state of agitation or excitement, as of the intellect or the feelings.
• noun a form of oxidation in which alcohol is converted into vinegar or acetic acid by the agency of a specific fungus (Mycoderma aceti) or series of enzymes. The process involves two distinct reactions, in which the oxygen of the air is essential. An intermediate product, acetaldehyde, is formed in the first process.
• noun the fermentation which saccharine bodies undergo when brought in contact with the yeast plant or Torula. The sugar is converted, either directly or indirectly, into alcohol and carbonic acid, the rate of action being dependent on the rapidity with which the Torulæ develop.
• noun the conversion of the urea of the urine into ammonium carbonate, through the growth of the special urea ferment.
• noun the decomposition of various forms of organic matter, through the agency of a peculiar worm-shaped vibrio, with formation of more or less butyric acid. It is one of the many forms of fermentation that collectively constitute putrefaction. See Lactic fermentation.
• noun Fermentations of this class are purely chemical reactions, in which the enzyme acts as a simple catalytic agent. Of this nature are the decomposition or inversion of cane sugar into levulose and dextrose by boiling with dilute acids, the conversion of starch into dextrin and sugar by similar treatment, the conversion of starch into like products by the action of diastase of malt or ptyalin of saliva, the conversion of albuminous food into peptones and other like products by the action of pepsin-hydrochloric acid of the gastric juice or by the ferment of the pancreatic juice.
• noun (Biol. & Med.) the theory that most if not all, infectious or zymotic disease are caused by the introduction into the organism of the living germs of ferments, or ferments already developed (organized ferments), by which processes of fermentation are set up injurious to health. See Germ theory.
• noun the fermentation which occurs on mixing a dilute solution of glycerin with a peculiar species of schizomycetes and some carbonate of lime, and other matter favorable to the growth of the plant, the glycerin being changed into butyric acid, caproic acid, butyl, and ethyl alcohol. With another form of bacterium (Bacillus subtilis) ethyl alcohol and butyric acid are mainly formed.
• noun the transformation of milk sugar or other saccharine body into lactic acid, as in the souring of milk, through the agency of a special bacterium (Bacterium lactis of Lister). In this change the milk sugar, before assuming the form of lactic acid, presumably passes through the stage of glucose.
• noun See Putrefaction.

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

• noun biochemistry Any of many anaerobic biochemical reactions in which an enzyme (or several enzymes produced by a microorganism) catalyses the conversion of one substance into another; especially the conversion (using yeast) of sugars to alcohol or acetic acid with the evolution of carbon dioxide
• noun A state of agitation or excitement; a ferment

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

• noun a state of agitation or turbulent change or development
• noun a process in which an agent causes an organic substance to break down into simpler substances; especially, the anaerobic breakdown of sugar into alcohol