equilibrium

equilibrium — noun

1. a condition in which opposing forces, influences, or processes are so evenly mat

1.nounB2
Definition

a condition in which opposing forces, influences, or processes are so evenly matched that no one side is stronger than the other and the whole system stays stable

Example

The region's economy achieved a new equilibrium after years of inflation and high unemployment.

collocation: 'achieve equilibrium' with abstract noun subject

Rafael adjusted the weights on both sides to bring the scale into equilibrium.

Common collocations
  • delicate equilibrium
  • stable equilibrium
  • economic equilibrium
  • political equilibrium
  • restore equilibrium
  • achieve equilibrium
  • disturb equilibrium
  • in equilibrium with
  • reach equilibrium
Synonyms
  • balance

    the common everyday word; equilibrium is more formal and technical

  • stability

    emphasises the lack of change over time rather than the equal weight of forces

  • parity

    focuses on equality of value, status, or amount, often in economics or politics

Antonyms
  • imbalance

    the direct opposite — a situation where forces are not equal

  • instability

    refers to a system that changes unpredictably rather than settling

Grammar Patterns

equilibrium + between + [plural noun]

in equilibrium + with + [noun]

Usage Note

Frequently used in formal or academic writing about economics, politics, ecology, and physics. Unlike the everyday word 'balance,' which is common in casual speech, 'equilibrium' carries a more technical or scholarly tone.

Common Mistakes

The two sides are in the equilibrium.
The two sides are in equilibrium.
When equilibrium describes a general state of balance, it is uncountable and does not take the article 'the.'
Scientists observed an equilibrium between temperature and pressure.
Scientists observed equilibrium between temperature and pressure.
The indefinite article 'an' should not be used before uncountable 'equilibrium.'

2. the ability to stay calm and in control of your emotions or thoughts, especially

2.nounB2
Definition

the ability to stay calm and in control of your emotions or thoughts, especially when facing difficult or stressful situations

Example

After the accident, it took Christopher several months to regain his emotional equilibrium.

collocation: 'regain one's equilibrium' after a shock

Practising yoga every morning helps Diya maintain her mental equilibrium throughout the day.

collocation: 'mental equilibrium' with 'maintain'

Common collocations
  • emotional equilibrium
  • mental equilibrium
  • psychological equilibrium
  • regain one's equilibrium
  • maintain one's equilibrium
  • keep one's equilibrium
  • lose one's equilibrium
  • shake one's equilibrium
  • disturb one's equilibrium
Synonyms
  • composure

    less formal, very common in everyday English; equilibrium is more formal

  • poise

    emphasises grace and dignity under pressure, not just calmness

  • self-possession

    focuses on control over one's reactions, similar register to equilibrium

Antonyms
  • agitation

    a state of nervousness or upset

  • anxiety

    a feeling of worry, nervousness, or unease

Grammar Patterns

[possessive] + equilibrium

keep/maintain/regain/lose + [possessive] + equilibrium

Usage Note

Almost always paired with a possessive determiner (my, his, her, their, one's). Common verbs used with this sense include keep, maintain, regain, lose, and disturb. The modifying adjectives are typically emotional, mental, or psychological.

Common Mistakes

She tried to keep equilibrium during the crisis.
She tried to keep her equilibrium during the crisis.
In the mental state sense, equilibrium requires a possessive determiner.

❌ 'I lost my emotional equilibrium after hearing the news of his passing.' is grammatically correct but very formal. In everyday conversation, speakers would more naturally say 'I lost my composure' or 'I got really upset.'

3. in chemistry, the condition of a reversible reaction in which the forward reacti

3.nounC1
Definition

in chemistry, the condition of a reversible reaction in which the forward reaction and the reverse reaction happen at the same speed, so that the amounts of the reactants and products stop changing over time

Example

In chemistry class, Ilan learned how raising the temperature affects the position of chemical equilibrium.

domain: 'chemical equilibrium' as a technical concept

The system reached equilibrium when the forward and reverse reaction rates became equal.

pattern: 'reach equilibrium' as a complete process

Common collocations
  • chemical equilibrium
  • dynamic equilibrium
  • static equilibrium
  • reach equilibrium
  • at equilibrium
  • equilibrium constant
  • equilibrium position
  • shift the equilibrium
Synonyms
  • steady state

    broader term used in many sciences for a system that does not change over time, though the mechanism differs

Grammar Patterns

reach equilibrium

at equilibrium

chemical equilibrium

dynamic equilibrium

Usage Note

Subject is typically a chemical system, reaction, or mixture. This sense can appear as an attributive noun in compounds such as equilibrium constant and equilibrium position, a pattern that is rare for other senses of the word. Often modified by the adjectives dynamic or static to distinguish two types of equilibrium.

Word family

  • equilibria
    nounC1
  • equilibrate
    verbC1
  • equilibration
    nounC1
  • equilibrium constant
    nounC1

Synonym discussion

Sense: noun/1

Equilibrium, balance, stability, and parity all describe situations where elements are arranged in a satisfactory or unchanging way, but they differ in scope and formality. Balance is by far the most common word and can be used in everyday contexts ('work-life balance', 'a balanced diet'), while equilibrium is more formal and technical, appearing in academic writing about economics, ecology, and physics. Stability focuses on resistance to change over time — a system can be stable without being in perfect balance. Parity is the narrowest term, used mainly for equality of value, quantity, or status in economics, law, or sports. For example, you would say 'the candidate struck a balance between experience and fresh ideas' (natural and common), not 'struck an equilibrium.' In scientific writing, however, 'the system reached equilibrium' is standard, while 'the system reached balance' would sound unscientific.

equilibrium ↗balance ↗stability ↗parity

Common collocations

Nouns

  • state of equilibrium
  • point of equilibrium
  • sense of equilibrium

Adverbs

Phrases

  • in a state of equilibrium
  • bring something into equilibrium
  • throw something out of equilibrium

Prepositions

  • in equilibrium with
  • out of equilibrium
  • into equilibrium

Etymology

LatinEnglish

From Latin aequilibrium, a combination of aequi- ('equal') and libra ('balance, scale'). Originally a physics term in the 1600s describing balanced forces on objects, the word gradually developed a general sense (balance of any opposing elements) and later a psychological sense (emotional calm). The chemical sense emerged in the 1800s as thermodynamics developed.