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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are stiffeningprogressive
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am 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.
“It probably would stiffen their spine,” said Brian Latell, a former CIA analyst who wrote a biography of Castro and his older brother Fidel Castro.
From The Wall Street Journal • May 21, 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
"This will only stiffen our resolve to ensure that we make Washington DC safe and beautiful," the Pentagon chief said.
From BBC • Nov. 26, 2025
In people with Alzheimer's, Aβ accumulates and causes arteries to stiffen, slowing the flow of fluids between brain tissue and cerebrospinal fluid.
From Science Daily • Nov. 11, 2025
Then Nathan was saying something to Lily as he started the car; it was making her stiffen.
From "It All Comes Down to This" by Karen English
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.
