# diaphragm

/ˈdaɪəˌfɹæm/ (US) · /dˈaɪəfɹˌæm/ (UK)

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

## Senses

### 1. anatomy: breathing muscle

noun · CEFR B2 · Technical

the large, flat muscle between your chest and stomach that helps you breathe.

For teachers: the primary muscle of respiration in mammals, separating the thoracic cavity from the abdominal cavity.

- Singers learn to breathe from the diaphragm to support their voice.
- During inhalation, the diaphragm contracts and moves downward, creating a vacuum that draws air into the lungs.

Usage: Usually used with the definite article 'the'.

### 2. photography: lens aperture

noun · CEFR C1 · Technical

a part of a camera lens that opens and closes to control how much light gets in.

For teachers: an adjustable thin opaque structure with a central aperture used to regulate the amount of light reaching a film or sensor.

- Adjusting the diaphragm changes the depth of field in your photo.
- The photographer narrowed the diaphragm to ensure that both the foreground flowers and the distant mountains remained in sharp focus.

### 3. contraception

noun · CEFR C1 · Technical

a small, flexible cup used by women as a method of birth control.

For teachers: a barrier contraceptive device consisting of a flexible silicone cup designed to cover the cervix.

- She spoke with her doctor about using a diaphragm for family planning.
- When used correctly with spermicide, the diaphragm provides an effective non-hormonal method of contraception.

### 4. audio: speaker part

noun · CEFR C2 · Technical

the thin part of a speaker or microphone that vibrates to make or record sound.

For teachers: a thin, semi-rigid membrane in an acoustic transducer that vibrates to produce or receive sound waves.

- The speaker's diaphragm was damaged, causing the sound to crackle.
- High-end headphones often utilize extremely lightweight diaphragms to achieve a faster transient response and greater clarity.

### 5. engineering: pressure barrier

noun · CEFR C2 · Technical

a flexible sheet that moves when the pressure on one side changes.

For teachers: a flexible partition between two chambers that distends in response to pressure differentials.

- The pump uses a rubber diaphragm to move the liquid through the pipes.
- The industrial valve failed because the internal diaphragm had perished after years of exposure to corrosive chemicals.

### 6. to adjust an aperture

verb · CEFR C2 · Technical

to change the size of the opening in a camera lens.

For teachers: to regulate or reduce the aperture of an optical system using a diaphragm.

- You may need to diaphragm the lens to get a clearer image in bright sun.
- The technician had to diaphragm the microscope carefully to eliminate the glare from the slide illumination.

Usage: Often used as the phrasal verb 'diaphragm down'.

## Examples

- Singers use their diaphragm to control their breath.
- The doctor explained that a hiccup is actually a sudden, involuntary contraction of the diaphragm.
- Effective breath support in classical vocal performance relies on the conscious engagement of the diaphragm to maintain a steady column of air throughout long melodic phrases.

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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.