Thesaurus.com
Dictionary.com
Showing results for stiffen.
Definitions

stiffen

[stif-uhn] / ˈstɪf ən /
VERB
make or become harder
Synonyms
STRONGEST
reinforce solidify stabilize strengthen
STRONG
anneal benumb brace cake candy cement chill clot coagulate condense congeal crystallize curdle firm fix freeze gel harden inflate inspissate jell jelly ossify petrify precipitate prop set starch steady tauten tense thicken
Antonyms
STRONGEST
weaken
STRONG
dilute dissolve heat liquefy melt separate soften thin unfix
WEAK
loosen

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.

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 involves the buildup of dense, fibrous tissue around the tumor, made up of cells and proteins that stiffen and inflame the area.

From Science Daily • Jan. 30, 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 will only stiffen our resolve to ensure that we make Washington DC safe and beautiful," the Pentagon chief said.

From BBC • Nov. 26, 2025

I felt myself stiffen a little as she kept playing with my hair.

From "Turtles All the Way Down" by John Green

Vocabulary lists containing stiffen

Mid-Air

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!