diaphragm

noun

1. 1

   a mechanical device in a camera that controls size of aperture of the lens

   the new cameras adjust the diaphragm automatically

2. 2

   electro-acoustic transducer that vibrates to receive or produce sound waves

3. 3

   a contraceptive device consisting of a flexible dome-shaped cup made of rubber or plastic; it is filled with spermicide and fitted over the uterine cervix

4. 4

   (anatomy) a muscular partition separating the abdominal and thoracic cavities; functions in respiration