An Etymological Dictionary of the German Language/Annotated/Gischt

by Friedrich Kluge

Gischt, older Gäscht, masculine, ‘yeast, foam,’ formed from the equivalent Middle High German jëst, gëst, masculine, corresponding to English yest, yeast, Dutch gest, ‘yeast.’ Allied to gischen (Middle High German gischen), older gäschen (Middle High German geschen, a variant of jësen). See gären, a factitive of Middle High German jësen.