Definition of "fermentation"

fermentation

/ˌfɜː(ɹ)mənˈteɪʃən/

noun
countable and uncountable, plural fermentations
1. (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
2. A state of agitation or excitement; a ferment.
  Quotations
  [T]he Grace that is then given to us is like a piece of Leven put into a lump of dough, and Faith and Repentance do in all the periods of our life put it into fermentation and activity.
  1678, Jeremy Taylor, “The History of the Life and Death of the Holy Jesus: […]. The First Part.”, in Antiquitates Christianæ: Or, the History of the Life and Death of the Holy Jesus: […], London: […] E. Flesher, and R. Norton, for R[ichard] Royston, […], ad section IX (Considerations upon the Baptizing, Fasting, and Temptation of the Holy Jesus by the Devil), discourse IV (Of Baptism), part II (Of Baptizing Infants), page 130
  The universal fusion of races, languages, and customs, which had gone on for four centuries under Roman rule, had produced a corresponding fusion of creeds, an universal fermentation of human thought and faith.
  1852 January – 1853 April, Charles Kingsley, Jun., “Preface”, in Hypatia: Or, New Foes with an Old Face. […], volume I, London: John W[illiam] Parker and Son, […], published 1853, pages xi–xii