n. - A dividing membrane or thin partition, commonly with an opening through it.
n. - The muscular and tendinous partition separating the cavity of the chest from that of the abdomen; the midriff.
n. - A calcareous plate which divides the cavity of certain shells into two parts.
n. - 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.
n. - A partition in any compartment, for various purposes.