thicken

verb

thick·​en ˈthi-kən 

thickened; thickening ˈthi-kə-niŋ 

ˈthik-

intransitive verb

1

a

: to become dense

the mist thickened

b

: to become concentrated in numbers, mass, or frequency

2

: to grow blurred or obscure

3

: to grow broader or bulkier

4

: to grow complicated or keen

the plot thickens

transitive verb

1

a

: to make thick, dense, or viscous in consistency

thicken gravy with flour

b

: to make close or compact

2

: to increase the depth or diameter of

3

: to make inarticulate : blur

alcohol thickened his speech

thickener

ˈthi-kə-nər 

ˈthik-

noun

Examples of thicken in a Sentence

I thickened the gravy with flour.

When the mixture thickens, add the remaining ingredients.

The fog thickened when night fell.

Recent Examples on the Web

Clouds thicken overnight with a few showers possible toward daybreak Sunday. — Kate Bilo, CBS News, 18 Sep. 2026

Pour in the tomato puree, mix gently, partially cover, and cook until the puree darkens and thickens and has mostly been absorbed by the rice, about 3 minutes. — ABC News, 17 Sep. 2026

Bring to a simmer over medium; cook until mixture is thickened, about 2 minutes. — Alana Al-Hatlani, Southern Living, 17 Sep. 2026

The clam chowder is perfectly balanced and not at all clumpy or overly thickened, and the lobster roll is one of the best in all of Boston. — Condé Nast, Condé Nast Traveler, 9 Sep. 2026

Word History

First Known Use

14th century, in the meaning defined at intransitive sense 1a

Rhymes for thicken

• chicken
• likin
• quicken
• sicken
• stricken
• indican

Kids Definition

thicken

verb

thick·​en ˈthik-ən 

thickened; thickening -(ə-)niŋ 

1

: to make or become thick, dense, or viscous

thicken gravy with flour

2

: to become complicated

the plot thickens

thickener

-(ə-)nər 

noun