Baker's yeast in a bowl.
baker's yeast definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a yeast (Saccharomyces cerevisiae) used in baking as a leavening, as for certain breads
baker's yeast definition by American Heritage Dictionary
A commercial preparation consisting of dried cells of one or more strains of the fungus Saccharomyces cerevisiae, used as a leavening in baking.