General English


  • noun a thin sheet of material used to separate parts or chambers

Cars & Driving

  • noun a thin, flexible membrane displaced under pressure, e.g. in vacuum units, often connected to a rod or other member to transmit movement


  • noun a thin flexible sheet that vibrates in response to sound waves to create an electrical signal, as in a microphone, or in response to electrical signals to create sound waves, as in a speaker


  • A stiffening member between two structural steel members, used to increase rigidity.
  • The web across a hollow masonry unit.
  • An instrument to measure the flow of water in pipes.


  • A vibrating membrane in a speaker. It produces a sound wave output in response to its electric input. Cones and domes are examples of commonly utilized diaphragms in speakers. Also called speaker diaphragm, or loudspeaker diaphragm.
  • A vibrating membrane in a microphone. It produces an electric output in response to its sound-wave input. Also called microphone diaphragm.
  • A pressure-sensitive element in some sensors, such as certain barometers.
  • A membrane, disk, adjustable opening, or other device or mechanism which serves to restrict or regulate the passage of a waves and/or matter, such as light waves or electrolytes.


  • The muscular partition separating the lung and abdominal cavity in mammals. Not usually traded separately except in beef cattle.

Media Studies

  • noun a curved muscular membrane separates the abdomen from the area around the lungs and is used in singing to control the breathing
  • noun a disc with an opening to control the amount of light that is allowed to enter a camera or other optical instrument


  • noun a thin layer of tissue stretched across an opening, especially the flexible sheet of muscle and fibre which separates the chest from the abdomen and moves to pull air into the lungs in respiration

Origin & History of “diaphragm”

The etymological notion underlying diaphragm is of a sort of ‘fence’ or ‘partition’ within the body. It comes via late Latin diaphragma from Greek diáphragma. this in turn was a derivative of diaphrássein ‘divide off, barricade’, a compound verb formed from the intensive prefix dia- and phrássein ‘fence in, enclose’. Originally in Greek diáphragma was applied to other bodily partitions than that between the thorax and the abdomen – to the septum which divides the two nostrils, for instance.