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

Example Sentences

If Ms. Gage wanted some celebratory leaven, she could have visited Dayton, Ohio’s many sites devoted to the Wright Brothers and their world-changing invention.

From The Wall Street Journal • Apr. 1, 2026

There was gloss and sass to leaven the tough stuff.

From Los Angeles Times • Mar. 27, 2024

I also used to leaven the proceedings with humor.

From Salon • Feb. 2, 2024

An hour or two each week grappling with wood planks or mixing batter can leaven a long and monotonous school day.

From Seattle Times • Oct. 13, 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