yeast

Etymology

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”).

noun

1. An often humid, yellowish froth produced by fermenting malt worts, and used to brew beer, leaven bread, and also used in certain medicines.
2. A single-celled fungus of a wide variety of taxonomic families.
   1. A true yeast or budding yeast in order Saccharomycetales.
      1. baker's yeast, Saccharomyces cerevisiae
         1. A compressed cake or dried granules of this substance used for mixing with flour to make bread dough rise.
      2. brewer's yeast, certain species of Saccharomyces, principally Saccharomyces cerevisiae and Saccharomyces carlsbergensis.
   2. Candida, a ubiquitous fungus that can cause various kinds of infections in humans.
      1. The resulting infection, candidiasis.
3. (figurative) A frothy foam.

verb

1. To ferment.
2. (of something prepared with a yeasted dough) To rise.
3. (African-American Vernacular, slang) To exaggerate.