Yeast
Old English, of Germanic origin; related to Dutch gist and German Gischt ‘froth, yeast’, from an Indo-European root shared by Greek zein ‘to boil’.
wiktionary
From Middle English yest, yeest, gest, gist, from Old English ġist, ġyst, from Proto-West Germanic *jestu, from Proto-Germanic *jestuz. Cognate with Saterland Frisian Jääst(“yeast”), West Frisian gêst, gist(“yeast”), Dutch gist(“yeast”), German Low German Gest(“yeast”), German Gischt(“sea foam”), Swedish jäst(“yeast”), Norwegian jest(“yeast”), Icelandic jöstur(“yeast”).
etymonline
yeast (n.)
Old English gist "yeast, froth," from Proto-Germanic *jest- (source also of Old Norse jastr, Swedish jäst, Middle High German gest, German Gischt "foam, froth," Old High German jesan, German gären "to ferment"), from PIE root *yes- "to boil, foam, froth" (source also of Sanskrit yasyati "boils, seethes," Greek zein "to boil," Welsh ias "seething, foaming").
