stiffen

stiffen — verb

1. to become rigid and resistant to bending, or to cause something to become like t

1.verbtransitive / intransitiveB2
Definition

to become rigid and resistant to bending, or to cause something to become like this, usually through cold, drying, or the addition of a firming substance.

Example

Nikhil waited for the glue to dry, watching the paper stiffen on the model airplane.

intransitive: [material] stiffens as [substance] dries

Before the party, Lisa stiffened the tablecloth with starch to make it look neat.

transitive: stiffen [thing] with [substance]

Common collocations
  • stiffen with starch
  • stiffen in the cold
  • stiffen [fabric/collar/cardboard]
Synonyms
  • harden

    more general — can apply to surfaces, food, cement, etc.

  • solidify

    implies becoming solid throughout, not just stiff on the surface

  • set

    specifically for substances like glue, cement, or jelly that become firm after a period

Antonyms
  • soften

    opposite process — becoming less firm and more pliable

  • loosen

    becoming less tight or rigid

Grammar Patterns

stiffen (something)

stiffen with [substance]

stiffen in [temperature/condition]

Usage Note

Frequently used for materials such as fabric, cardboard, or rubber that react to temperature changes or added substances. Can describe either a natural process (intransitive) or an intentional action by a person (transitive).

Common Mistakes

The bread stiffened in the oven.
The bread hardened in the oven.
Stiffen implies becoming rigid or unbending, not just firm; bread in an oven does not stiffen, it hardens.
I stiffened the rope by pulling it tight.
I tightened the rope by pulling it.
Ropes are pulled tight, not stiffened; stiffen refers to the material's own rigidity, not tension.

2. to suddenly hold your body still and tight, or to become more serious and less c

2.verbintransitiveB2
Definition

to suddenly hold your body still and tight, or to become more serious and less casual in manner, often as a reaction to fear, anger, nervousness, or a tense social situation.

Example

When the manager walked in, the whole team stiffened and stopped chatting.

intransitive: group stiffens upon [event]

Ife stiffened as the dog growled, not daring to move or even breathe.

intransitive: stiffen as [threatening event] happens

Common collocations
  • stiffen with fear
  • stiffen at the sound
  • stiffen in surprise
  • stiffen when [someone] enters
Synonyms
  • tense up

    more common in everyday speech — same meaning but less formal

  • freeze

    implies stopping all movement from fear or shock

  • brace oneself

    suggests preparing for an impact rather than a startled reaction

Antonyms
  • relax

    to become calm and loose again

  • loosen up

    informal — to stop being tense or formal

Grammar Patterns

stiffen at [stimulus]

stiffen with [emotion]

stiffen when [event happens]

Usage Note

Often describes a quick, involuntary reaction to a specific trigger — a sound, a person's arrival, bad news, or a tense moment. Can refer to either the body (muscles, shoulders) or the general mood of a situation. Not used for planned or deliberate actions.

Common Mistakes

She stiffened her muscles before lifting the box.
She tensed her muscles before lifting the box.
Stiffen for body reactions is typically involuntary and intransitive; 'tense' or 'tighten' is better for deliberate muscle preparation.

3. to make laws, rules, or standards stricter and harder to avoid, or for someone's

3.verbtransitive / intransitiveC1
Definition

to make laws, rules, or standards stricter and harder to avoid, or for someone's attitude, determination, or opposition to become stronger and more unwavering.

Example

The government has stiffened the penalties for using a phone while driving.

transitive: stiffen [penalties/rules]

Otis's resolve stiffened when he remembered why he had started this project.

intransitive: [resolve/determination] stiffens

Common collocations
  • stiffen penalties
  • stiffen requirements
  • stiffen standards
  • stiffen [someone's] resolve
  • stiffen resistance
Synonyms
  • toughen

    very similar in meaning; often used for laws and attitudes

  • tighten

    focuses on making rules harder to bypass or avoid

  • strengthen

    broader — can apply to many things from economy to relationships

Antonyms
  • weaken

    opposite — make rules or attitudes less strict

  • soften

    make requirements less severe or attitudes more flexible

  • relax

    formal — to make rules less strict

Grammar Patterns

stiffen [rules/penalties/requirements]

stiffen [resolve/determination/resistance]

Usage Note

The object must be something abstract — rules, penalties, requirements, standards, or personal qualities like resolve, resistance, or opposition. Not used for physical objects in this sense. Common in formal, legal, and institutional contexts.

Common Mistakes

The company stiffened its prices.
The company raised its prices.
Stiffen is not used for prices or fees; use 'raise,' 'increase,' or 'tighten' instead.
She stiffened her offer to buy the house.
She improved her offer.
Offers can be increased or improved, not stiffened.

Word family

  • stiff
    adjectiveB1
  • stiffly
    adverbB2
  • stiffness
    nounB2
  • stiffener
    nounC1

Synonym discussion

Sense: verb/1

Stiffen, harden, solidify, and set all describe becoming firmer, but they differ in what kinds of things they describe. Stiffen specifically means becoming rigid and harder to bend — it applies to materials like fabric, cardboard, or rubber. Harden is broader: cement hardens, butter hardens, hearts harden. Solidify means becoming solid throughout, not just on the surface. Set is the most specific — it describes a substance (glue, cement, jelly) reaching its final firm state after a period. For example: 'The glue set in twenty minutes, stiffening the paper' sounds natural, but 'The concrete stiffened' sounds odd — concrete hardens or sets, it does not stiffen.

harden ↗solidify ↗set ↗stiffen ↗

Common collocations

Nouns

  • stiffen [fabric]
  • stiffen [collar]
  • stiffen [cardboard]
  • stiffen [penalties]
  • stiffen [rules]
  • stiffen [resolve]
  • stiffen [requirements]

Adverbs

  • stiffen noticeably
  • stiffen visibly
  • stiffen suddenly
  • stiffen gradually

Phrases

  • stiffen into silence
  • stiffen with fear
  • stiffen in the cold

Prepositions

  • stiffen at
  • stiffen with
  • stiffen in
  • stiffen into
  • stiffen against

Etymology

Old EnglishMiddle EnglishModern English

Stiffen is formed from the adjective 'stiff' (from Old English 'stīf', meaning rigid or unbending) plus the suffix '-en', which turns adjectives into verbs meaning 'to make or become'. The word has been in English since at least the 1400s, originally describing physical rigidity and later extending to abstract and emotional meanings.