Definition of: diaphragm

(dī′ə·fram) noun
1. Anat. An important muscle used in respiration, situated between the thoracic and abdominal cavities; the midriff.
2. Any dividing membrane or partition.
3. Any device supposed to resemble a diaphragm in shape, appearance, or elasticity, as the thin vibrating disk of a telephone or phonograph, or the flexible rubber sheet of a vacuum brake.
4. The porous cup of a voltaic cell.
5. Optics A perforated disk whose aperture may be reduced in order to cut off marginal rays in a camera or telescope.
—v.t. To act upon or furnish with a diaphragm. [<L diaphragma <Gk. <dia- across + phragma a fence]
—di·a·phrag·mat·ic (dī′ə·frag·mat′ik) adjective
—di′a·phrag·mat′i·cal·ly adverb