YEAST (O.E. giest or gyst; the root yes-, to boil, ferment, is seen in Sansk. nir-yasa, exudations from trees, and Gr. ftiiv, to boil), a cellular organism produced in the alcoholic fermentation of saccharine liquids (see FUNGI, FERMENTATION, BREWING).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)