What does "yeast" mean?

1. (baking/brewing ingredient) a tiny fungus used to make bread rise or to make beer and wine. 2. (biology) a type of very small living thing that is a fungus. 3. (to ferment) to bubble and change chemically, like when making beer. 4. (to exaggerate) to make a story seem bigger or more important than it really is.

How do you use "yeast"?

Uncountable when referring to the substance generally; countable when referring to specific strains or packets.

yeast

n. · v.

US //ˈjist// UK //jˈiːst// yeast

1 baking/brewing ingredient (n.)
B2 Upper Intermediate Cooking

a tiny fungus used to make bread rise or to make beer and wine.

a unicellular fungus, specifically of the genus Saccharomyces, used as a leavening agent in baking and a fermenter in brewing.

Example

You need to mix the yeast with warm water and sugar before adding it to the flour.

Example

The baker monitored the temperature carefully, as excessive heat would kill the yeast and prevent the dough from rising properly.

Usage

Uncountable when referring to the substance generally; countable when referring to specific strains or packets.
- leaven
- ferment
2 biology (n.)
C1 Advanced Technical Science

a type of very small living thing that is a fungus.

any of various small, single-celled fungi that reproduce by budding or fission.

Example

Scientists study how different types of yeast react to various sugars.

Example

The researcher isolated a specific strain of yeast from the skin of the grapes to study its unique fermentation properties.
- fungus
- micro organism

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3 to ferment (v.)
C2 Proficiency Technical Archaic Science

to bubble and change chemically, like when making beer.

to undergo or cause fermentation; to become frothy through the action of fungi.

Example

The mixture began to yeast as the natural sugars broke down.

Example

The liquid was left in the vat to yeast for several days until the desired alcohol content was achieved.
4 to exaggerate (v.)
C1 Advanced Slang Informal

to make a story seem bigger or more important than it really is.

to inflate the truth or provide an exaggerated account of an event.

Example

He is always yeasting about how much money he makes at his new job.

Example

Don't listen to his version of the story; he tends to yeast whenever he wants to impress a new audience.

Teacher's tip

This slang usage is relatively niche and often found in specific regional dialects; learners should use it cautiously.
- understate

Origin

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”).