1 B1 neutral
For muscles or joints to become painful and difficult to move, typically after inactivity, exercise, or cold.
"After sitting at the desk all day, my back had completely stiffened up."
inseparable
stiffen up
B1 neutral inseparable transitive/intransitive
To become stiff, rigid, or tense, especially in muscles or posture.
In plain English
When your body becomes hard to move or bend, especially after sitting still or being cold.
What does "stiffen up" mean?
3 meanings, ordered from most common to least. Color-coded by CEFR level.
2 B2 neutral
To become tense or rigid in posture or manner, often due to nervousness or formality.
"She stiffened up when her boss walked into the room."
inseparable
3 C1 idiomatic neutral
For resolve, opposition, or resistance to become stronger and more determined.
"The government's harsh response only stiffened up opposition to the new law."
inseparable
Literal vs figurative
Words literally mean
To become more stiff or rigid.
Actually means
When your body becomes hard to move or bend, especially after sitting still or being cold.
Usage tip
Most commonly intransitive, referring to muscles, joints, or the body. Can also be transitive when referring to making something more rigid. Also used figuratively for attitudes or resolve hardening.
Words that pair with "stiffen up"
Natural word combinations native speakers use most often.
muscles joints neck back posture resolve
How to conjugate "stiffen up"
The five tense forms you'll use most often.
Base
stiffen up
I/you/we/they
3rd person
stiffens up
he/she/it
Past simple
stiffened up
yesterday
Past participle
stiffened up
have + pp
-ing form
stiffening up
continuous
Hear "stiffen up" in the wild
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Keep exploring
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