yeast

play

noun \ ˈyēst , especially Southern and Midland US ˈēst \

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

But the yeast still need fuel to produce these products.

— ben panko, Smithsonian, "Could Astronauts Harvest Nutrients From Their Waste?," 24 Aug. 2017
Yeast doughnut filled with blackberry/blueberry jam and topped with midnight blue icing.

— joyce smith, kansascity, "You can eat or wear these KC solar eclipse specials," 18 Aug. 2017
Earthy Belgian yeast was noticeable in the background, in a good way — no overwhelming funk or leather notes.

— todd haefer, the (appleton, USA TODAY, "Beer Man: Bayside is a farmhouse ale fit for summer," 13 Aug. 2017
And that doesn't just mean blood: Your vaginal discharge actually contains a bunch of white blood cells, which help keep the vagina's bacteria and yeast levels balanced, says ob-gyn Candace Howe, M.D.

— suzannah weiss, Glamour, "How Your Vagina Changes When You Get Sick," 10 Aug. 2017
The idea of terroir, of expressing the place where something is made and adding on the layer of microbial or yeast fermentation and bacteria fermentation as the source or main genesis of that flavor.

— michael klein, Philly.com, "Promoting local booze and bacteria at Martha in Kensington," 10 Aug. 2017
Ostrov has now created a prototype for such a device, using yeast.

— ed yong, The Atlantic, "Turning Baker’s Yeast Into a Disease Sensor," 18 July 2017
The Science Part Yeast digests sugar to convert into alcohol; adding grains (normally a main ingredient in beer) gives the yeast a more balanced diet and produces a tastier beverage.

— francine maroukian, Popular Mechanics, "You Need to Know About Real, Boozy Ginger Beer," 7 July 2017
Kefir is another way of fermenting milk that has more probiotics (beneficial microbes) than yogurt, often carrying twice as many bacterial strains along with some beneficial yeast strains.

— carrie dennett, The Seattle Times, "Kefir: even better than yogurt for gut health?," 4 July 2017

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

See Words from the same year

yeast Synonyms

Synonyms

boost, encouragement, goad, impetus, incentive, incitation, incitement, instigation, momentum, motivation, provocation, spur, stimulant, stimulus, impulse

Antonyms

counterincentive, disincentive

Related Words

inducement, invitation; antecedent, cause, consideration, grounds, motive, occasion, reason; catalyst, catalyzer, fuel, spark

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

Other Biochemistry Terms

bile, biodegradable, capsaicin, keratin, metabolism

YEAST Defined for English Language Learners

yeast

play

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

play

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

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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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