Source : Webster's Revised Unabridged Dictionary (1913)

Septum \Sep"tum\, n.; pl. {Septa}. [L. septum, saeptum, an
   inclosure, hedge, fence, fr. sepire, saepire, to hedge in,
   inclose.]
   1. A wall separating two cavities; a partition; as, the nasal
      septum.

   2. (Bot.) A partition that separates the cells of a fruit.

   3. (Zo["o]l.)
      (a) One of the radial calcareous plates of a coral.
      (b) One of the transverse partitions dividing the shell of
          a mollusk, or of a rhizopod, into several chambers.
          See Illust. under {Nautilus}.
      (c) One of the transverse partitions dividing the body
          cavity of an annelid.

Source : WordNet®

septum
     n 1: (anatomy) a dividing partition between two tissues or
          cavities
     2: a partition or wall especially in an ovary
     [also: {septa} (pl)]