harden

harden — verb

1. When a soft or liquid substance hardens, or when something hardens it, it become

1.verbtransitive / intransitiveB1
Definition

When a soft or liquid substance hardens, or when something hardens it, it becomes firm, solid, or stiff — for example, cement setting, wax cooling, or glue drying.

Example

The cement will harden within a few hours, so you need to shape it quickly.

intransitive: material + harden + time phrase

Cold temperatures harden the ground, making it difficult to dig in winter.

Common collocations
  • cement hardens
  • glue hardens
  • wax hardens
  • harden into a solid
  • harden quickly
  • harden fully
Synonyms
  • solidify

    more formal, often about liquids changing state

  • stiffen

    specifically about becoming rigid, can apply to fabrics or body parts

  • set

    common for cement, jelly, glue — implies a chemical curing process

Antonyms
  • soften
  • melt

    applies to substances that change from solid to liquid

Grammar Patterns

material + harden

agent + harden + material

harden + into + form

Usage Note

This sense describes a physical change in materials. The intransitive use ('The concrete hardened') is very common; the transitive use ('The cold hardened the ground') usually names a natural force or process as the agent.

Common Mistakes

I hardened the butter in the fridge for ten minutes.
I left the butter to harden in the fridge for ten minutes.
'harden' describes a natural process, not a deliberate action carried out by a person.

2. When someone's attitude, opinion, voice, or facial expression hardens — or when

2.verbtransitive / intransitiveB2
Definition

When someone's attitude, opinion, voice, or facial expression hardens — or when something causes this change — that person's feelings grow more severe, less flexible, and less open to compromise. For instance, a politician hardening a stance after public pressure.

Example

The mayor hardened her stance on traffic fines after several serious accidents.

collocation: harden stance/position/attitude

Hamza's voice hardened when he described the unfair treatment his team received.

Common collocations
  • harden one's stance
  • harden one's position
  • harden one's heart
  • harden against
  • attitude hardens
  • opinion hardens
Synonyms
  • stiffen

    emphasises a sudden, visible change in posture or attitude

  • toughen

    implies making demands or rules stricter

  • strengthen

    broader; can apply to resolve, belief, or conviction

Antonyms
  • soften

    the most direct opposite for attitudes and positions

  • relent

    become less severe after being firm

Grammar Patterns

opinion/attitude + harden

harden + possessive + stance/position

opinion + harden + against

Usage Note

Subject is often 'attitude', 'position', 'stance', 'voice', 'face', or 'expression'. Common in political, business, and interpersonal conflict contexts. The intransitive pattern with 'against' ('opinion hardens against') is typical in journalism.

Common Mistakes

She hardened to study harder.
She hardened her determination to study harder.
'harden' takes a direct object (determination, resolve) rather than a to-infinitive.

3. To make someone emotionally less sensitive, less easily shocked, or better able

3.verbtransitive / intransitiveB2
Definition

To make someone emotionally less sensitive, less easily shocked, or better able to cope with difficult, dangerous, or unpleasant conditions — for example, a nurse becoming hardened to blood after years of work, or soldiers hardened by harsh training.

Example

Years of working in a busy emergency room had hardened the nurses to blood and injury.

passive: be hardened to [something]

The soldiers were hardened by six months of training in freezing mountain conditions.

passive: be hardened by [experience]

Common collocations
  • be hardened to
  • be hardened by
  • harden someone to suffering
  • harden someone to criticism
  • hardened by experience
Synonyms
  • toughen

    more active sense of building strength, not just numbness

  • desensitise

    formal, focuses on loss of sensitivity, often negative

  • inure

    very formal, rarely used in everyday speech

Antonyms
  • sensitise

    make more aware or responsive

  • soften

    make more tender or compassionate

Grammar Patterns

be hardened to [something]

be hardened by [experience]

experience + hardens + person

Usage Note

Frequently used in the passive voice ('be hardened by/to'). The object is usually a person or group. The variant 'be hardened to' carries the nuance of becoming indifferent or numb; 'be hardened by' emphasises the cause.

Common Mistakes

Cold weather hardened him to stay outside.
Cold weather hardened him to outdoor conditions.
'harden someone to' is followed by a noun phrase (the thing one is no longer sensitive to), not a verb.

harden — noun

Word family

  • hard
    adjectiveA1
  • hardness
    nounB1
  • hardened
    adjectiveB2
  • hardening
    nounB2

Synonym discussion

Sense: verb/1

All four verbs describe a substance becoming firmer, but they differ in context. 'Solidify' is the most general and formal term — it simply means to change from a liquid or semi-liquid into a solid ('The lava solidified into rock'). 'Stiffen' focuses on becoming rigid or unbending; it is used for fabrics, body parts, or materials that remain dry ('The collar stiffened after spraying starch'). 'Set' is the everyday word for substances that cure chemically, such as cement, jelly, glue, or plaster ('Leave the jelly in the fridge to set'), and it implies a planned or expected change. 'Cake' means to form a thick, dry, hardened layer on a surface ('Mud caked on his boots'), often with an unpleasant or messy connotation. In everyday speech, 'harden' is the most natural word for gradual physical firming (e.g., wax, cement, glue), while 'set' is preferred for materials that go through a specific curing time.

solidify ↗stiffen ↗set ↗cake ↗

Common collocations

Nouns

Adverbs

Phrases

  • harden one's resolve
  • harden one's heart

Prepositions

Etymology

Old EnglishProto-GermanicEnglish

From Old English 'heardian' (to become hard), derived from the adjective 'heard' (hard). Related forms exist across Germanic languages — German 'härten', Dutch 'harden', Old Norse 'harðna'. The physical sense has been in English since before the 12th century, while the figurative meanings (emotional toughening, attitude stiffening) developed by the 16th century.