[{"Bold_text": "noun", "List Items": ["a substance, as yeast or baking powder, that causes fermentation and expansion of dough or batter.", "fermented dough reserved for producing fermentation in a new batch of dough.", "an element that produces an altering or transforming influence."]}, {"Bold_text": "verb (used with object)", "List Items": ["to add leaven to (dough or batter) and cause to rise.", "to permeate with an altering or transforming element."]}]