yeast

The word “yeast” means a microscopic fungus used to ferment dough or brew alcohol. In plain terms, a living microorganism used in baking (to make bread rise) and brewing (to turn sugar into alcohol).

“Yeast” is pronounced yeest (/jist/ in IPA).

Here is “yeast” used in a sentence: “She added a packet of yeast to the flour to make the dough rise.”

Depending on how it is used, “yeast” can be a noun and a verb.

The word “yeast” comes from Old English. From Old English ġist/ġyst, from a Germanic root related to foam or froth — the same root behind the German word for sea foam.

“Yeast” is an uncommon word in modern English.

“Yeast” has 2 distinct senses listed in this dictionary. The most common is: a microscopic fungus used to ferment dough or brew alcohol.

Yeast is a microscopic fungus that ferments dough biologically, producing carbon dioxide over time through a living organism, whereas baking powder is a chemical leavening agent that reacts instantly with moisture and heat. Yeast typically requires proofing time, while baking powder works immediately in baking.

Yes, "yeast" can function as a verb meaning to ferment or cause something to rise, though the noun use referring to the fungus itself is far more common. As a verb it describes the action or process rather than the organism.

No, yeast is also used to brew alcohol, since the same fermentation process that makes dough rise also converts sugars into alcohol and carbon dioxide in beverages like beer and wine. Its dual role in baking and brewing comes from this shared fermentation ability.