Yeast

yēst, n. the froth of malt liquors in fermentation: the vegetable growth to which fermentation is due, of value in brewing, baking, .: ( Shak. ) spume or foam of water.— v.i. to ferment.— ns. Yeast′ine , the state of being yeasty or frothy; Yeast′-plant , a small plant causing alcoholic fermentation in saccharine liquids; Yeast′-pow′der , a baking powder.— adj. Yeast′y , like yeast: frothy, foamy: unsubstantial. [A.S. gist , gyst ; Ger. gäscht , gischt .]