diaphragm

(noun) a mechanical device in a camera that controls size of aperture of the lens. Synonyms: stop. Example: "The new cameras adjust the diaphragm automatically."

(noun) (anatomy) a muscular partition separating the abdominal and thoracic cavities; functions in respiration. Synonyms: midriff.

(noun) 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. Synonyms: pessary, contraceptive diaphragm.

(noun) electro-acoustic transducer that vibrates to receive or produce sound waves.