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ˈyēst How to pronounce yeast (audio)
 especially Southern and Midland US  ˈēst
: a yellowish surface froth or sediment that occurs especially in saccharine liquids (such as fruit juices) in which it promotes alcoholic fermentation, consists largely of cells of a fungus (such as the saccharomyces, Saccharomyces cerevisiae), and is used especially in the making of alcoholic liquors and as a leaven in baking
: a commercial product containing yeast fungi in a moist or dry medium
: a unicellular fungus that is present and functionally active in yeast, usually has little or no mycelium, and reproduces by budding
: any of various similar fungi
archaic : the foam or spume of waves
: something that causes ferment or activity
were all seething with the yeast of revoltJ. F. Dobie
yeast-like adjective
or less commonly yeastlike
ˈyēst-ˌlīk How to pronounce yeast (audio)
 especially Southern and Midland US  ˈēst-


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yeasted; yeasting; yeasts

Examples of yeast in a Sentence

Noun taxation without representation proved to be the yeast of rebellion
Recent Examples on the Web
Research has indicated that active ingredients like vitamin B, vitamin E, trace yeast, and inositol—the benefits of which can be furthered through fermentation, as noted—can serve to smooth and moisturize hair and skin. Calin Van Paris, Vogue, 19 Nov. 2023 Let this stand for 5 minutes so the yeast can activate. Karla Walsh, Better Homes & Gardens, 14 Nov. 2023 Wondering if instructions should have indicated dissolving the yeast in warm milk, with a tsp of sugar before proceeding /w reminder of recipe? Anna Theoktisto, Southern Living, 14 Nov. 2023 Its production process encapsulates centuries of craftsmanship, carefully blending premium rice, pure water, yeast, and koji fungus. Tokyo Halfie, Condé Nast Traveler, 9 Oct. 2023 It’s derived from malassezia, a type of yeast found on the skin. Petra Guglielmetti, Glamour, 13 Nov. 2023 In fact, a microbiome of bacteria and yeast naturally live on the skin. Claire McCarthy, M.d., Parents, 13 Nov. 2023 It is made of leftover yeast from local breweries and bakeries; requires a multiweek fermentation process; involves salt, and maybe onions and celery; and is an excellent source of vitamins. Natasha Frost Abigail Varney, New York Times, 12 Nov. 2023 Common fungal infections include athlete's foot, jock itch, ringworm, and vaginal yeast infections.8 The urinary tract is a common site for infections. Barbie Cervoni, Ms, Rd, Cdces, Cdn, Health, 18 Oct. 2023
Make dough: Add eggs, shortening, sugar, salt, 2 cups of the flour, and remaining 1 cup warm water to yeast mixture. Southern Living Test Kitchen, Southern Living, 15 Oct. 2023 Add shortening mixture to yeast mixture along with 4 cups bread flour. Micah A Leal, Southern Living, 20 July 2023 To create tiny morphine factories, scientists added to yeast genetic components from poppy, sugar beets, and a soil bacterium. Carl Engelking, Discover Magazine, 20 May 2015 Spring Valley Apple Cider Vinegar Capsules are preservative-free, artificial coloring and flavoring-free, and also yeast, wheat, milk, lactose, and sugar-free. Amber Smith, Discover Magazine, 14 Oct. 2022 Lichens are symbiotic organisms of fungi, algae and possibly yeast that live off each other, not your tree. Jessica Damiano, Chicago Tribune, 17 Jan. 2023 Some dogs, on the other hand, are allergic to yeast. Amber Smith, Discover Magazine, 18 Oct. 2022 Here, the liquid becomes wine thanks to yeast that transforms the grape juice into alcohol and carbon dioxide. Karla Walsh, Better Homes & Gardens, 29 Aug. 2022 With bread and yeast hard to find early in the pandemic, more people began baking sourdough bread at home. Carol Deptolla, Milwaukee Journal Sentinel, 26 Jan. 2022 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'yeast.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History



Middle English yest, from Old English gist; akin to Old High German jesen, gesen to ferment, Greek zein to boil

First Known Use


before the 12th century, in the meaning defined at sense 1a


1819, in the meaning defined above

Time Traveler
The first known use of yeast was before the 12th century

Dictionary Entries Near yeast

Cite this Entry

“Yeast.” Dictionary, Merriam-Webster, Accessed 30 Nov. 2023.

Kids Definition


: a one-celled fungus that produces alcohol during the process of fermentation
also : any of various similar fungi
: a yellowish foamy material that may occur on the surface of sweet liquids (as fruit juices) undergoing fermentation and that consists chiefly of yeast cells and carbon dioxide
: a commercial product containing living yeast cells that is used mostly in the making of alcoholic beverages and as a leaven especially in baking bread
: something that causes motion or activity

Medical Definition


: a unicellular chiefly ascomycetous fungus (as of the family Saccharomycetaceae) that has usually little or no mycelium, that typically reproduces asexually by budding, and that includes forms (as Saccharomyces cerevisiae) which cause alcoholic fermentation and are used especially in the making of alcoholic beverages and leavened bread
: a yellowish surface froth or sediment that occurs especially in sugary fermenting liquids (as fruit juices) and consists chiefly of yeast cells and carbon dioxide
: a commercial product containing yeast cells in a moist or dry medium
yeastlike adjective

More from Merriam-Webster on yeast

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