Septum

Part of speech: noun (n.)

1. A wall separating two cavities; a partition; as, the nasal septum.

2. A partition that separates the cells of a fruit.

3. One of the radial calcareous plates of a coral.

4. One of the transverse partitions dividing the shell of a mollusk, or of a rhizopod, into several chambers. See Illust. under Nautilus.

5. One of the transverse partitions dividing the body cavity of an annelid.