Leaven, as a noun, is that which causes transformation. It’s the source of yeast that makes your bread rise, it’s the risen bread, and it’s anything that changes the nature of something else.

Coming through Old French from the Latin verb levare, which means “to raise,” leaven changes everything. It makes dough go from flat to loaf, and it’s also the term to describe the risen dough before it’s baked. And leaven can be anything that causes transformation — "Winning the lottery will be the leaven that allows you to travel the world." Additionally it’s a verb: "When you bake bread, you leaven the dough to make it rise."

Definitions of leaven
  1. noun
    a substance used to produce fermentation in dough or a liquid
    synonyms: leavening
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    baking powder
    any of various powdered mixtures used in baking as a substitute for yeast
    a leaven of dough in which fermentation is active; used by pioneers for making bread
    barm, yeast
    a commercial leavening agent containing yeast cells; used to raise the dough in making bread and for fermenting beer or whiskey
    yeast cake
    small cake of compressed moist yeast
    brewer's yeast
    yeast used in fermenting beer
    a stringy slimy substance consisting of yeast cells and bacteria; forms during fermentation and is added to cider or wine to produce vinegar
    type of:
    a particular kind or species of matter with uniform properties
  2. noun
    an influence that works subtly to lighten or modify something
    synonyms: leavening
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    type of:
    a factor whose effects cannot be accurately assessed
  3. verb
    cause to puff up with a leaven
    synonyms: prove, raise
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    type of:
    bring up, elevate, get up, lift, raise
    raise from a lower to a higher position
Word Family

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