# ignition

/ˌɪɡˈnɪʃən/ (US) · /ɪɡnˈɪʃən/ (UK)

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

## Senses

### 2. engine system

noun · CEFR B2

the electrical system in a vehicle that starts the engine.

For teachers: the mechanism or electronic system responsible for igniting the fuel-air mixture in an internal combustion engine.

- The car wouldn't start because there was a problem with the ignition.
- Modern vehicles often replace the traditional ignition system with electronic push-button starts that communicate wirelessly with a key fob.

Usage: usually functions as an uncountable noun when referring to the system as a whole.

### 3. key switch

noun · CEFR B2

the place in a car where you put the key to start the engine.

For teachers: the physical switch or receptacle into which a key is inserted to activate a vehicle's engine.

- He left his keys in the ignition and accidentally locked the car doors.
- The driver turned the key in the ignition, but the engine only produced a faint clicking sound, suggesting a dead battery.

Usage: often used with the preposition 'in'.

### 4. nuclear fusion

noun · CEFR C2 · Technical

the point when a nuclear reaction creates enough energy to keep itself going.

For teachers: the state in which a thermonuclear fusion reaction becomes self-sustaining, requiring no further external energy input.

- Scientists are working hard to achieve ignition in fusion power plants.
- Achieving fusion ignition represents a major milestone in clean energy research, as it proves the plasma can maintain its own temperature through internal heating.

Usage: uncountable in this specialized physical sense.

Teaching tip: This is a highly specific term in physics; students will likely only encounter it in science news or academic papers.

## Examples

- He turned the key in the ignition, but the car didn't start.
- The pilot checked the fuel levels and the ignition system before attempting to take off.
- Engineers are developing a more efficient ignition sequence to reduce the amount of unburned fuel released during the initial combustion phase of the rocket launch.

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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.