diaphragm

From Ancient Greek διάφραγμα (diáphragma, “partition”), from διά (diá, “across”) and φράγμα (phrágma, “barrier”), from the verb φράσσω (phrássō).

• IPA^(key): /ˈdaɪəˌfɹæm/

diaphragm (plural diaphragms)

1. (anatomy) In mammals, a sheet of muscle separating the thorax from the abdomen, contracted and relaxed in respiration to draw air into and expel air from the lungs; also called thoracic diaphragm.
2. (anatomy) Any of various membranes or sheets of muscle or ligament which separate one cavity from another.
3. A contraceptive device consisting of a flexible cup, used to cover the cervix during intercourse.
4. (mechanics) A flexible membrane separating two chambers and fixed around its periphery that distends into one or other chamber as the difference in the pressure in the chambers varies.
5. (acoustics) In a speaker, the thin, semi-rigid membrane which vibrates to produce sound.
6. (optics, photography) A thin opaque structure with a central aperture, used to limit the passage of light into a camera or similar device.
7. (chemistry) A permeable or semipermeable membrane.
   • 1921, Wilder Dwight Bancroft, Applied Colloid Chemistry: General Theory‎, page 207:

     The mass of liquid transported through a porous diaphragm in a given time is directly proportional to the current.

8. (construction) A floor slab, metal wall panel, roof panel or the like, having a sufficiently large in-plane shear stiffness and sufficient strength to transmit horizontal forces to resisting systems.

diaphragm (third-person singular simple present diaphragms, present participle diaphragming, simple past and past participle diaphragmed)

1. (optics, photography) To reduce lens aperture using an optical diaphragm.
   • 1870, D. Appleton & Co., Appletons' Annual Cyclopædia and Register of Important Events of the Year 1869‎, page 43:

     He employs an equatorial with an object-glass having a focal length of five metres, and which was diaphragmed down to eight centimetres.

2. To act as a diaphragm, for example by vibrating.
   • 1996, Tom Drozda et al., Tool and Manufacturing Engineers Handbook, vol. VIII: Plastic Part Manufacturing‎, →ISBN, page 16-24:

     The holes and burning are caused by the part diaphragming at 20000-40000 cycles/second.

• 
  The thoracic diaphragm.
• 
  A contraceptive diaphragm.
• 
  A mechanical diaphragm.
• 
  An acoustic diaphragm.