diaphragm

American  

[dahy-uh-fram] / ˈdaɪ əˌfræm /

noun

diaphragms plural

1. Anatomy.

   1. a muscular, membranous or ligamentous wall separating two cavities or limiting a cavity.

   2. the partition separating the thoracic cavity from the abdominal cavity in mammals.

2. Physical Chemistry.

   1. a porous plate separating two liquids, as in a galvanic cell.

   2. a semipermeable membrane.

3. a thin disk that vibrates when receiving or producing sound waves, as in a telephone, microphone, speaker, or the like.

4. Also called pessary.  a thin, dome-shaped device, usually of rubber, for wearing over the uterine cervix during sexual intercourse to prevent conception.

5. a plate with a hole in the center or a ring that is placed on the axis of an optical instrument, as a camera, and that controls the amount of light entering the instrument.

6. a plate or web for stiffening metal-framed constructions.

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verb (used with object)

1. to furnish with a diaphragm.

2. to reduce the aperture of (a lens, camera, etc.) by means of a diaphragm.

diaphragm British  

/ ˈdaɪəˌfræm, ˌdaɪəfræɡˈmætɪk /

noun

1. anatomy any separating membrane, esp the dome-shaped muscular partition that separates the abdominal and thoracic cavities in mammals

2. a circular rubber or plastic contraceptive membrane placed over the mouth of the uterine cervix before copulation to prevent entrance of sperm

3. any thin dividing membrane

4. Also called: stop.  a disc with a fixed or adjustable aperture to control the amount of light or other radiation entering an optical instrument, such as a camera

5. a thin disc that vibrates when receiving or producing sound waves, used to convert sound signals to electrical signals or vice versa in telephones, etc

6. chem

   1. a porous plate or cylinder dividing an electrolytic cell, used to permit the passage of ions and prevent the mixing of products formed at the electrodes

   2. a semipermeable membrane used to separate two solutions in osmosis

7. botany a transverse plate of cells that occurs in the stems of certain aquatic plants

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diaphragm Scientific  

/ dī′ə-frăm′ /

1. The large muscle that separates the chest cavity from the abdominal cavity in mammals and is the principal muscle of respiration. As the diaphragm contracts and moves downward, the lungs expand and air moves into them. As the diaphragm relaxes and moves upward, the lungs contract and air is forced out of them.

2. A thin, flexible disk, especially in a microphone or telephone receiver, that vibrates in response to sound waves to produce electrical signals, or that vibrates in response to electrical signals to produce sound waves.

3. A contraceptive device consisting of a thin flexible disk, usually made of rubber, that is designed to cover the cervix of the uterus to prevent the entry of sperm during sexual intercourse.

4. An optical device in a camera or telescope that regulates the amount of light that enters the lens or optical system. The diaphragm consists of a disk with a circular opening of variable diameter.

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diaphragm Cultural  

1. A dome-shaped structure made up of muscle and connective tissue that separates the abdominal cavity from the thorax and functions in respiration. By movement of the diaphragm, air is either drawn into the lungs or forced out of them.

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Discover More

The term diaphragm can also refer to a small flexible cap, usually made of rubber, that fits over the cervix and is used for contraception.

Other Word Forms

Derived Forms

• diaphragmatic
  adjective
• diaphragmatically
  adverb

Inflected Forms

Nouns

• diaphragms
  plural

Etymology

Origin of diaphragm

1350–1400; Middle English diafragma < Late Latin diaphragma < Greek diáphragma the diaphragm, midriff, equivalent to dia- dia- + phrágma a fence

Explanation

Ever had the hiccups? Then you're familiar with your diaphragm, the large muscle that stretches across your midriff to support your lungs and help you breathe. When you get the hiccups, your diaphragm spasms uncontrollably. The Greek word diáphragma referred to the body's midriff and came from the root phrágma, meaning "fence." This led to the Middle English diafragma, also referring to the muscular stretch below the lungs. The idea of a diaphragm as a contraceptive first surfaced in 1933. A diaphragm is also the part of the camera called a "stop," which adjusts the amount of light, and it is a thin, vibrating disc used in electronics to transfer sound.

Example Sentences

See Examples For:

diaphragm diaphragms

Hiccups are caused by the involuntary spasming of the diaphragm, typically as a result of an irritated phrenic nerve.

From BBC ● Dec. 28, 2025

After the operation, doctors will assess whether Bolsonaro can undergo an additional procedure: blockage of the phrenic nerve, which controls the diaphragm, for recurrent hiccups, Birolini said.

From Barron's ● Dec. 25, 2025

Typical features include frequent deep sighs, rapid breathing, forceful exhalation from the abdomen, or chest breathing without proper diaphragm use, which prevents the lungs from fully expanding.

From Science Daily ● Nov. 10, 2025

For example, “Pinky could conclude only that the strength of the floor diaphragm where the trench headers bisected the slab was inadequate.”

From The Wall Street Journal ● Oct. 17, 2025

I take a deep breath, so deep it feels like my diaphragm hits my knees, and sing the highest note I can at full voice.

From "What the Night Sings" by Vesper Stamper

Their use today is limited to more niche applications, including the chlorine industry’s asbestos diaphragms, or sheet gaskets or parts used to make vehicle braking systems.

From Washington Post ● Feb. 19, 2023

The use of asbestos diaphragms has been declining and now accounts for about one-third of the chlor-alkali production in the U.S.,

From Seattle Times ● Apr. 5, 2022

Restrictions on asbestos diaphragms and sheet gaskets for commercial use would take effect two years after the effective date of the final rule.

From New York Times ● Apr. 5, 2022

Their earbud stems are 4.4mm shorter than LG’s previous models, and they have improved drivers and diaphragms which LG claims offers more bass without impacting clarity.

From The Verge ● Jul. 26, 2021

“Just try to realize it,” he said, and his voice sent a strange thrill quivering along their diaphragms.

From "Brave New World" by Aldous Huxley

Related Words

• abstinence
• condom
• contraceptive
• family planning
• pill
• vasectomy