RhymeZone: leaven definitions

Definitions of leaven:

noun: an influence that works subtly to lighten or modify something
Example: "His sermons benefited from a leavening of humor"
noun: a substance used to produce fermentation in dough or a liquid
verb: cause to puff up with a leaven
Example: "Unleavened bread"
name: A surname (very rare: popularity rank in the U.S.: #82185)