\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.