A microscopic fungus consisting of single oval cells that reproduce by budding, and are capable of converting sugar into alcohol and carbon dioxide, used in baking and brewing.

The baker added yeast to the dough to make it rise.

A commercial product containing yeast cells, used as a leavening agent in baking.

She bought a packet of yeast from the store to bake bread.

An agent of ferment or activity, often used metaphorically.

The new ideas acted as a yeast in the stagnant organization, sparking innovation.

yeastverb

To ferment or cause to ferment by means of yeast; to rise with the action of yeast.

Let the wort yeast for several days until the bubbling subsides.