# equilibrium

/ˌikwəˈɫɪbɹiəm/ (US) · /ˌiːkwɪlˈɪbɹiəm/ (UK)

Source: https://englishreference.com/word/equilibrium
Updated: 2026-06-20

## Senses

### 1. physical or general balance

noun · CEFR C1 · Academic

a state where different parts or forces are balanced and stable.

For teachers: a condition in which all acting influences are cancelled by others, resulting in a stable, balanced, or unchanging system.

- The scales reached equilibrium when the weights on both sides were exactly the same.
- The ecosystem maintained a delicate equilibrium for centuries until the introduction of invasive species disrupted the local food chain.

Usage: Often used with the verbs 'maintain', 'disturb', or 'restore'.

### 2. chemical balance

noun · CEFR C1 · Technical

the point in a chemical reaction where the forward and backward changes happen at the same speed.

For teachers: the state of a reversible chemical reaction in which the rates of the forward and reverse reactions are equal, resulting in no net change in concentrations.

- In a closed bottle of soda, the liquid and gas reach equilibrium.
- The chemist adjusted the temperature to shift the equilibrium of the reaction, thereby increasing the yield of the desired product.

### 3. mental calmness

noun · CEFR C2 · Formal · Literary

a calm state of mind where you feel balanced and in control.

For teachers: a state of emotional or mental balance; composure.

- Yoga helps her recover her equilibrium after a stressful day at the office.
- It took several months of quiet reflection for him to regain his mental equilibrium following the sudden collapse of his business empire.

## Examples

- The liquid reached equilibrium when the temperature stopped changing.
- Yoga helps me maintain my physical and mental equilibrium during a busy work week.
- In a closed chemical system, dynamic equilibrium is achieved when the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in concentration.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.