n. [ L. diaphragma, Gr. &unr_;, fr. &unr_; to fence by a partition wall; dia` through + &unr_;, &unr_;, to fence, inclose; prob. akin to L. fareire to stuff: cf. F. diaphragme. See Farce. ] 1. A dividing membrane or thin partition, commonly with an opening through it. [ 1913 Webster ]

2. (Anat.) The muscular and tendinous partition separating the cavity of the chest from that of the abdomen; the midriff. [ 1913 Webster ]

3. (Zool.) A calcareous plate which divides the cavity of certain shells into two parts. [ 1913 Webster ]

4. (Opt.) A plate with an opening, which is generally circular, used in instruments to cut off marginal portions of a beam of light, as at the focus of a telescope. [ 1913 Webster ]

5. (Mach.) A partition in any compartment, for various purposes. [ 1913 Webster ]

Diaphragm pump, one in which a flexible diaphragm takes the place of a piston. [ 1913 Webster ]

a. [ Cf. F. diaphragmatique. ] Pertaining to a diaphragm; as, diaphragmatic respiration; the diaphragmatic arteries and nerves. [ 1913 Webster ]

. An adjustable diaphragm, reminiscent of the iris of the eye in its action, by which the diameter of an approximately circular opening may be controlled, as for regulating the aperture of a lens; it consists of a number of movable thin curved plates fastened at regular intervals around the inside of a ring, the positions of which are simultaneously adjusted by a single knob on the outside of the lens. It is used in cameras and microscopes. [ Webster 1913 Suppl. +PJC ]