An agent that causes rising, fermentation, or ferment; leaven.(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.
Use "leavening" in a sentence
"The men were mostly Swiss, but with a leavening from the German states, and they were a sober, steady battalion that Wellesley planned to lead to the Inner Palace to protect its contents and its harem from the ravages of the attackers."
"Ministers are employed in leavening places, in leavening souls, with the gospel."
"Regarding the coconut cake, all the ingredients technically are kosher for Passover, but it hasn't been _certified_ basically, a rabbi checks to make sure that it's been made on equipment that's been completely cleansed of all leavening aka chametz."