stiffen

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

v make stiff or stiffer

Stiffen the cream by adding gelatine”
Antonyms:
loose, loosen
make loose or looser
Types:
starch
stiffen with starch
buckram
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

v become stiff or stiffer

“He stiffened when he saw his boss enter the room”
Antonyms:
loose, loosen, relax
become loose or looser or less tight
Types:
rigidify
become rigid
Type of:
change
undergo a change; become different in essence; losing one's or its original nature

v restrict

stiffen the regulations”
Synonyms:
constrain, tighten, tighten up
Type of:
bound, confine, limit, restrain, restrict, throttle, trammel
place limits on (extent or access)

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