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."

Definitions of stiffen
  1. verb
    make stiff or stiffer
    Stiffen the cream by adding gelatine”
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    loose, loosen
    make loose or looser
    stiffen with starch
    stiffen with or as with buckram
    ossify, petrify, rigidify
    make rigid and set into a conventional pattern
    type of:
    alter, change, modify
    cause to change; make different; cause a transformation
  2. verb
    become stiff or stiffer
    “He stiffened when he saw his boss enter the room”
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    loose, loosen, relax
    become loose or looser or less tight
    become rigid
    type of:
    undergo a change; become different in essence; losing one's or its original nature
  3. verb
    stiffen the regulations”
    synonyms: constrain, tighten, tighten up
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    type of:
    bound, confine, limit, restrain, restrict, throttle, trammel
    place limits on (extent or access)
Word Family

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