leaven

American  

[lev-uhn] / ˈlɛv ən /

noun

1. a substance, as yeast or baking powder, that causes fermentation and expansion of dough or batter.

2. fermented dough reserved for producing fermentation in a new batch of dough.

3. an element that produces an altering or transforming influence.

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verb (used with object)

1. to add leaven to (dough or batter) and cause to rise.

2. to permeate with an altering or transforming element.

leaven British  

/ ˈlɛvən /

noun

1. any substance that produces fermentation in dough or batter, such as yeast, and causes it to rise

2. a piece of such a substance kept to ferment a new batch of dough

3. an agency or influence that produces a gradual change

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verb

1. to cause fermentation in (dough or batter)

2. to pervade, causing a gradual change, esp with some moderating or enlivening influence

Etymology

Origin of leaven

First recorded in 1300–50; Middle English levain, levein, leven, from Anglo-French levein, levain, Old French levain, from Vulgar Latin levāmen (unrecorded) “means of raising or lifting,” from Latin levāmen “alleviation, mitigation, relief,” derivative of levā(re) “to raise, lift up; relieve, reduce” + -men noun suffix

Explanation

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."

Example Sentences

“Weapons” has something for everyone: jump scares for horrorphiles, nods to classics like “Rashomon” and “Magnolia” for film buffs, and more than a few laughs to leaven the tension.

From The Wall Street Journal • Nov. 26, 2025

That’s in keeping with a director who likes to leaven something profound with something ordinary.

From Seattle Times • May 28, 2024

There was gloss and sass to leaven the tough stuff.

From Los Angeles Times • Mar. 27, 2024

In the evening we will start with the first dough and when it's complete we let it leaven and rise overnight.

From Salon • Apr. 8, 2023

A leaven of love was left, it is true— Lancelot, Gareth, Aglovale and a few old dodderers like Sir Grummore and Sir Palomides: but the tone was set elsewhere.

From "The Once and Future King" by T. H. White

Related Words

• imbue
• infuse