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

Reduce the heat and simmer for 4–5 minutes, stirring occasionally, until the sauce thickens slightly. — Monti Carlo, AJC.com, 5 Sep. 2026

Reduce heat so mixture is at a simmer and cook, stirring occasionally, until thickened to the consistency of chili, 15–18 minutes. — Kendra Vaculin, Bon Appetit Magazine, 4 Sep. 2026

Bring to a simmer and cook until liquid thickened and reduced by 1/3, about 5 to 8 minutes. — Elizabeth Nelson, Southern Living, 2 Sep. 2026

The cells thicken a patient’s blood, putting them at higher risk for life-threatening heart attacks, strokes, and blood clots. — Jason Mast, STAT, 31 Aug. 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