# inertia

/ˌɪˈnɝʃə/ (US) · /ɪnˈɜːʃɐ/ (UK)

Source: https://englishreference.com/word/inertia
Updated: 2026-08-27

## Senses

### 1. physics

noun · CEFR C1 · Technical

the way an object keeps moving in the same direction unless something stops it.

For teachers: the physical property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.

- The car kept sliding on the ice because of its own inertia.
- The spacecraft utilized its own inertia to maintain a constant velocity through the vacuum of space without further fuel consumption.

Usage: Uncountable in this scientific context.

### 2. unwillingness to change

noun · CEFR C1 · Academic

a feeling of not wanting to move, act, or change a situation.

For teachers: a tendency to remain unchanged or a lack of motivation to initiate action.

- Bureaucratic inertia made it very difficult to change the old company rules.
- The government's failure to address the housing crisis was largely attributed to political inertia and a fear of upsetting the status quo.

Usage: Often used with 'bureaucratic', 'political', or 'institutional'.

### 3. medical

noun · CEFR C2 · Technical

a condition where a part of the body, like the uterus during birth, stops working as hard as it should.

For teachers: a state of sluggishness or lack of activity in an organ, specifically referring to the failure of the uterus to contract sufficiently during childbirth.

- The doctors were concerned about uterine inertia during the long labor.
- Primary uterine inertia may occur if the muscle wall is overstretched, leading to a failure in the progression of the first stage of labor.

Usage: Usually uncountable; typically appears in the phrase 'uterine inertia'.

## Examples

- The company's growth stopped because of management inertia.
- Overcoming the inertia of a large bureaucracy requires significant political will and a clear plan for reform.
- In physics, the mass of an object determines its inertia, while in social psychology, the term describes the tendency for individuals to maintain existing habits despite changing circumstances.

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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.