DIAPHRAGM

noun a partition in any compartment, for various purposes.

2. diaphragm ·noun a dividing membrane or thin partition, commonly with an opening through it.

3. diaphragm ·noun a calcareous plate which divides the cavity of certain shells into two parts.

4. diaphragm ·noun the muscular and tendinous partition separating the cavity of the chest from that of the abdomen; the midriff.

5. diaphragm ·noun 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.