I. ˈdīəˌfram, -raa(ə)m noun
( -s )
Etymology: Middle English diafragma, from Late Latin diaphragma, from Greek, partition, diaphragm, from diaphrassein, diaphrattein to barricade, from dia- + phrassein, phrattein to enclose, fence in — more at farce
1. : a body partition of muscle and connective tissue ; specifically : the partition separating the chest and abdominal cavities in mammals that by its contraction and relaxation varies the relative size and the internal pressure of these cavities and thereby plays an important role in such activities as breathing, defecation, and parturition and that in man has the form of an obliquely placed domed sheet, higher in front than behind, attached to the xiphoid cartilage, the six or seven lower ribs and their cartilages, and the lumbar vertebrae — see hiccup
2. : a dividing membrane or thin partition especially in a tube
3. : any of various more or less rigid partitions in the bodies or shells of invertebrate animals: as
a. : the membrane separating the heart from the rest of the body of an insect
b. : a calcareous partition extending into the cavity of the shell of a slipper limpet
c. : a chitinous shelf extending from the hydrotheca about the base of a hydranth
d. : a partition dividing the zooecia of some bryozoans into two chambers
4.
a. : the constriction in the neck of the nucule in the stoneworts
b. : a transverse septum in a stem (as at the nodes of a scouring rush or in the pith of some woody stems)
5. : a device (as a perforated plate) that limits the aperture of a lens or optical system : stop — see iris diaphragm
6. : a thin flexible often metallic disk that vibrates when struck by sound waves (as in a microphone) or that vibrates to produce sound waves (as in a telephone receiver or loudspeaker)
7. : a thin plate or partition between parallel parts of a structural steel member (as of a bridge) used to give rigidity to the member
8. : a molded cap usually of thin rubber fitted over the uterine cervix to act as a mechanical contraceptive barrier
9. : a moving grid of lead strips used for producing sharper X-ray images by eliminating the oblique rays that pass through them before reaching the film
II. transitive verb
( -ed/-ing/-s )
1. : to equip with a diaphragm : fit a diaphragm to
2. : to cut down the aperture of (a lens or mirror) by means of a diaphragm