yeast

noun \ ˈyēst , especially Southern and Midland US ˈēst \

Updated on: 20 Apr 2018

Definition of yeast

1 a : 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

b : a commercial product containing yeast fungi in a moist or dry medium

c (1) : a unicellular fungus that is present and functionally active in yeast, usually has little or no mycelium, and reproduces by budding

(2) : any of various similar fungi

2 archaic : the foam or spume of waves

3 : something that causes ferment or activity

were all seething with the yeast of revolt
—J. F. Dobie

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yeast-like

or less commonly yeastlike play \ˈyēst-ˌlīk, especially Southern and Midland US ˈēst-\ adjective

See yeast defined for English-language learners

See yeast defined for kids

Examples of yeast in a Sentence

taxation without representation proved to be the yeast of rebellion

Recent Examples of yeast from the Web

Both of these can be processed by a set of enzymes (or the yeast that produce the enzymes), which turn them into alcohol—a process that humans started working on millennia ago with highly desirable side effects.

— chris lee, Ars Technica, "Lumber’s lure: Thanks to physics, viable biofuel may grow in the woods," 5 Apr. 2018
His expertise in yeast launched a career as an executive for brewers and distillers.

— james r. hagerty, WSJ, "Pearse Lyons Used Brewing Expertise to Create Maker of Animal-Health Products," 23 Mar. 2018
The saison yeast adds a funky depth that keeps the beer interesting, but 1818 remains accessible enough for the Blue Moon and white wine crowds.

— josh noel, chicagotribune.com, "Illinois' bicentennial beer finally arrives, but is it good?," 15 Mar. 2018
Chad Robertson, of San Francisco’s cultishly loved bakery Tartine, has done so many collaborations that his sourdough starter is everywhere from New York to Stockholm, as iconic as a gurgling blob of yeast can be.

— catherine cusick, Longreads, "The Best Food Is Somewhere Else," 14 Mar. 2018
Chad Robertson, of San Francisco's cultishly loved bakery Tartine, has done so many collaborations that his sourdough starter is everywhere from New York to Stockholm, as iconic as a gurgling blob of yeast can be.

— ryan bradley, GQ, "How Pop-Ups Took Over America’s Restaurants," 7 Mar. 2018
Instead, the yeast can chill and develop this nutty, chewy flavor that’s noticeably complex.

— alex beggs, Bon Appetit, "Be a Person Who Makes Focaccia on the Regular," 6 Mar. 2018
Place 3 more noodles on top, finish layering the veggie mixture, top with sauce and sprinkle the nutritional yeast.

— susan selasky, Detroit Free Press, "Cardiologist Joel Kahn's push for plant-based lifestyle is outlined in new book," 25 Feb. 2018
Season with salt and pepper and stir in nutritional yeast.

— sarah karnasiewicz, Health.com, "3 Creative Whole30 Breakfasts You Can Make Even When You’re Half-Asleep," 22 Jan. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'yeast.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of yeast

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

NEW! Time Traveler

First Known Use: before 12th century

in the meaning defined at sense 1a

See Words from the same year

yeast Synonyms

Phrases

shot in the arm;

Other Food Terms

Reuben, calamari, chuck, curry, edamame, foie gras, hummus, leaven, nonpareil, peel

yeast

verb

Definition of yeast

intransitive verb

: ferment, froth

Recent Examples of yeast from the Web

Same for dozens of styles of fish stew, yeasted rolls, cakes, and pies found around the world.

— National Geographic, "The Secret History of the World's Priciest Spice," 3 May 2017

First Known Use of yeast

1819

in the meaning defined above

See Words from the same year

NEW! Time Traveler

Other Biochemistry Terms

bile, biodegradable, capsaicin, keratin, metabolism

YEAST Defined for English Language Learners

yeast

noun

Definition of yeast for English Language Learners

: a type of fungus that is used in making alcoholic drinks (such as beer and wine) and in baking to help make dough rise

YEAST Defined for Kids

yeast

noun \ ˈyēst \

Definition of yeast for Students

1 : a single-celled fungus that ferments sugar to produce alcohol and carbon dioxide

2 : a commercial product containing living yeast cells that is used in baking to make dough rise and in the making of alcoholic beverages (as wine)

Medical Dictionary

yeast

noun \ ˈyēst \

medical Definition of yeast

1 : 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

2 : 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

3 : a commercial product containing yeast cells in a moist or dry medium

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