Yeast

How to spell yeast

5 letters · 1 syllable

How to pronounce yeast

What does yeast mean?

1. nounA microscopic fungus used to ferment sugars, making bread rise and producing alcohol in brewing.

Yeast in a sentence

• The bread failed to rise because the yeast was past its expiry date.

• Home brewers add yeast to the cooled wort to start fermentation.

Where does yeast come from?

Language of origin: Germanic

Yeast comes from the Old English word gist (also spelled gyst), which named the frothy foam that rises on top of fermenting liquids such as ale and wort. It traces back to the Proto-Germanic root that gave related words in Dutch (gist) and German (Gischt, meaning froth or spray), and ultimately to an ancient Indo-European root meaning to boil, bubble, or foam. That same boiling sense connects it distantly to the Greek verb zein, 'to boil', which is why fermentation and seething share a root idea. Over the centuries the initial g sound softened and the spelling shifted toward the modern form, with the tricky 'ea' digraph settling in to represent the long e sound. The spelling trap is precisely that 'ea': the word sounds like it could begin 'yee-', yet it keeps the older 'ea' vowel pairing rather than a doubled e.

How the word is built

• yeast (a single Old English root, gist/gyst, meaning the foam of fermentation; no prefix or suffix)