stiffen
Americanverb (used with object)
verb (used without object)
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to become stiff.
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to become suddenly tense, rigid, or taut, as in bracing oneself for or drawing back from shock, fear, or displeasure.
He stiffened, expecting to hear the worst.
verb
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to make or become stiff or stiffer
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(intr) to become suddenly tense or unyielding
Other Word Forms
Derived Forms
Inflected Forms
Participles
Conjugated Forms
Present
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stiffensimple
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stiffenssimple
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have stiffenedperfect
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has stiffenedperfect
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am stiffeningprogressive
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are stiffeningprogressive
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is stiffeningprogressive
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have been stiffeningperfect progressive
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has been stiffeningperfect progressive
Past
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stiffenedsimple
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had stiffenedperfect
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was stiffeningprogressive
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were stiffeningprogressive
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had been stiffeningperfect progressive
Future
Etymology
Origin of stiffen
Explanation
To stiffen is to become stiff or unbending. If your legs stiffen during a long plane flight, you'll want to stretch them out once you land. You can stiffen something deliberately, like when you stiffen a package with cardboard to protect it in the mail. You can also stiffen in reaction to something: "The spooky creaking sounds upstairs made us stiffen in terror." The earliest sense of this verb was "make steadfast," from a now-obsolete meaning of stiff, "gain strength."
Vocabulary lists containing stiffen
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
These are, Mr. Freymann writes, “tempting targets,” but seizing them could stiffen the resolve of Taiwan and its Western friends.
From The Wall Street Journal ● May 14, 2026
She has also vowed to stiffen prison sentences and to impose a state of emergency in areas worst hit by crime.
From Barron's ● Feb. 1, 2026
Calling the eradication of extortion “one of the great challenges” facing Mexico, Sheinbaum pledged to bolster enforcement, stiffen penalties and increase safeguards for anyone receiving threats.
From Los Angeles Times ● Dec. 16, 2025
This leads the muscles to weaken and stiffen over time and ultimately impacts how you walk, talk, eat and breathe.
From BBC ● Dec. 4, 2025
And this caused her to stiffen with a tentative anger against Florence, and with pride and fear.
From "Go Tell It on the Mountain" by James Baldwin
US Defence Secretary Pete Hegseth responded to the deaths with a post on X that said: "Godspeed, heroes. Their sacrifice only stiffens our resolve."
From BBC ● Jul. 19, 2026
Once the pH returns to normal, the tissue stiffens again and locks into its new form.
From Science Daily ● May 28, 2026
The biggest reason is that our maximum heart rate slows with age, and the heart muscle stiffens, reducing its pumping effectiveness.
From Barron's ● May 23, 2026
More than 13% of Americans 75 and older have the condition, in which the aortic valve stiffens and narrows.
From The Wall Street Journal ● Apr. 25, 2026
And I can't talk, but I tap lightly on Alicia's cane, and she stiffens, then smiles slightly, and motions with her head and eyebrows, urging me to get going.
From "Things Not Seen" by Andrew Clements
Others argued the particles stiffened the surrounding material like glue.
From Science Daily ● May 13, 2026
And sure enough, as UConn’s shots started falling and its defense stiffened against Boozer’s attacks, the deficit narrowed.
From The Wall Street Journal ● Mar. 30, 2026
They reckon it may have stiffened the resolve of the German public and discouraged rebels within the dying Nazi regime.
From MarketWatch ● Mar. 12, 2026
The barrels -- bound tightly with rope, their fabric skins stiffened and darkened with lacquer -- inevitably recall the Gulf's vast hydrocarbon wealth.
From Barron's ● Feb. 16, 2026
The giant Norseman stiffened and fell back into the collapsed spice bin with a final wallop.
From "The Many Assassinations of Samir, the Seller of Dreams" by Daniel Nayeri
IPF is a chronic, progressive lung disease characterized by irreversible scarring and stiffening of lung tissue.
From Barron's ● Mar. 30, 2026
It’s hard to imagine a greater accomplishment than to achieve peace while stiffening the sinews of deterrence.
From The Wall Street Journal ● Mar. 1, 2026
It smashed 300-pound spheres swinging on a pendulum into a fuselage panel to deliberately damage it, causing one of the stiffening rods to break, then repeatedly applied loads representative of those in flight 40,000 times.
From Seattle Times ● Apr. 15, 2024
Further analysis showed that the discs from diabetic rats exhibited a stiffening of collagen fibrils, with a higher concentration of non-enzymatic cross-links.
From Science Daily ● Feb. 13, 2024
Papa didn’t get mad much, but Hanako could see tension building in his face, in his stiffening body.
From "A Place to Belong" by Cynthia Kadohata
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
