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Synonyms

stiffen

American  
[stif-uhn] / ˈstɪf ən /

verb (used with object)

  1. to make stiff.


verb (used without object)

  1. to become stiff.

  2. 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.

stiffen British  
/ ˈstɪfən /

verb

  1. to make or become stiff or stiffer

  2. (intr) to become suddenly tense or unyielding

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Etymology

Origin of stiffen

First recorded in 1490–1500; stiff + -en 1

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."

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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.

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

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

The effort to scrap the provision to stiffen penalties drew sweeping criticism from the governor and on social media.

From Los Angeles Times • May 1, 2025

The sight seemed to stiffen his resolve, and he nodded.

From "Harry Potter And The Chamber Of Secrets" by J. K. Rowling

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