Anatomy .

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

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

Physical Chemistry .

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

a semipermeable membrane.

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

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

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.

a plate or web for stiffening metal-framed constructions.

to furnish with a diaphragm.

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