Definition of "yeast" []

• Any of various unicellular fungi of the genus Saccharomyces, especially S. cerevisiae, reproducing by budding and from ascospores and capable of fermenting carbohydrates. (noun)
• Any of various similar fungi. (noun)
• Froth consisting of yeast cells together with the carbon dioxide they produce in the process of fermentation, present in or added to fruit juices and other substances in the production of alcoholic beverages. (noun)
• A powdered or compressed commercial preparation, having yeast cells and inert material such as meal and used chiefly as a leavening agent or as a dietary supplement. (noun)
• Foam; froth. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Their flavor become more intense and complex with the longer the yeast is allowed to develop."
• "Set aside for 5-10 minutes, until the yeast is activated and bubbly."
• "Just let me know what the name of the yeast is and where I might find it."