Definition of septum

• n. - A wall separating two cavities; a partition; as, the nasal septum.
• n. - A partition that separates the cells of a fruit.
• n. - One of the radial calcareous plates of a coral.
• n. - One of the transverse partitions dividing the shell of a mollusk, or of a rhizopod, into several chambers. See Illust. under Nautilus.
• n. - One of the transverse partitions dividing the body cavity of an annelid.