leaven
definition: an influence that works subtly to lighten or modify something
example: The sermons benefited from the leaven of humor.
speech part: noun
synonyms:
leavening
definition: a substance used to produce fermentation in dough or a liquid
example:
speech part: noun
synonyms:
leavening
definition: cause to puff up with a leaven
example: unleavened bread
speech part: verb
synonyms:
raise