<p><strong>Noun:</strong></p><ul><li>any of various small, single-celled fungi of the phylum <em>Ascomycota</em> that reproduce by fission or budding, the daughter cells often remaining attached, and that are capable of fermenting carbohydrates into alcohol and carbon dioxide.</li><li>any of several yeasts of the genus <em>Saccharomyces</em>, used in brewing alcoholic beverages, as a leaven in baking breads, and in pharmacology as a source of vitamins and proteins.</li><li>spume; foam.</li><li>ferment; agitation.</li><li>something that causes ferment or agitation.</li></ul>