||[Dec. 17th, 2009|02:15 pm]
Historical Origins of English Words and Phrases
yeast, n. [yeest, yēst]
-Though we now consider yeast to be any fungi of the genus Saccharomyces (especially S. cerevisiae), which reproduces by budding and from ascospores and is capable of fermenting carbohydrates, Middle English yest, yeest specifically referred to the froth of fermenting beer. The Middle English term was developed from Late Old English gist ' yeast,' which first appeared around 1000 CE. Scholars are not sure of the Germanic ancestor of our English word, but they do believe it to be a Western Germanic word that also produced Middle High German gest 'foam, froth' and Old High German jesan 'to ferment.' Whatever the source is, it sprung from prehistoric Indo-European jes-, yes-.
If anyone knows the definition of this PIE root, would you please let us know? I've been searching for about an hour now but just can't find it. I think this calls for a new reference book purchase. :)