stiffen

1 of 2

verb

stiff·​en ˈsti-fən 

stiffened; stiffening ˈsti-fə-niŋ 

ˈstif-niŋ

transitive verb

: to make stiff or stiffer

intransitive verb

: to become stiff or stiffer

stiffener

ˈsti-fə-nər 

ˈstif-nər

noun

stiffener

2 of 2

noun

stiff·​en·​er -f(ə)nə(r) 

plural -s

: one that stiffens: such as

a

: a worker who sizes hats

b

: something (such as buckram or a piece of paperboard) used for stiffening a manufactured article

specifically : counter entry 5 sense 5

c

: any of a number of vertical angles secured at intervals across the entire width of the web of a large plate girder to prevent buckling

d

: an angle iron, channel, or other structural shape used to increase the rigidity of plating on a ship's bulkhead

called also stiffening bar

e

: a structural member other than a flat sheet used to reinforce the frame of an aircraft compare stringer

f

: an alcoholic bracer

Synonyms of stiffen

Verb

• strengthen

Examples of stiffen in a Sentence

Verb

She stiffened when he grabbed her shoulder.

The dogs stiffened in alarm.

The law would stiffen penalties for tax evasion.

Recent Examples on the Web

Verb

Davidsen bucks up her balky husband with a bloodthirsty holler, stiffens her voice against doubt, and, in her final sleepwalking scene, taps into the tender stratum of Lady Macbeth’s subconscious. — Justin Davidson, Vulture, 23 Sep. 2026

The Chiefs’ defense stiffened and Indy faced a fourth-and-8 from the 15-yard line. — Pete Grathoff, Kansas City Star, 21 Sep. 2026

Over time, smoking can narrow and stiffen blood vessels and accelerate cardiovascular disease. — Katia Hetter, CNN Money, 16 Sep. 2026

But after a quick touchdown drive to take a 34-27 lead, the Oregon defense stiffened, and closed out the win with back-to-back stops. — Ian Miller Outkick, FOXNews.com, 6 Sep. 2026

Word History

First Known Use

Verb

15th century, in the meaning defined at transitive sense

Rhymes for stiffen

• griffon
• gryphon
• tiffin

Kids Definition

stiffen

verb

stiff·​en ˈstif-ən 

stiffened; stiffening -(ə-)niŋ 

: to make or become stiff or stiffer

stiffener

-(ə-)nər 

noun