ˈseptəm noun
( plural sep·ta -tə ; or septums )
Etymology: New Latin, from Latin septum, saeptum enclosure, fence, wall, from sepire, saepire to hedge in, enclose, from sepes, saepes fence, hedge; akin to Greek haimos copse, thicket, haimasia stone wall
1. : a dividing wall or membrane: as
a. : a wall separating two plant cells or two cavities or masses (as in a compound ovary or fruit) — called also dissepiment
b. : nasal septum
c. : crural septum
d. : a narrow dividing layer of rock material separating larger features of the rock fabric
e. : one of the transverse partitions dividing the shell of a cephalopod or a rhizopod into chambers
f. : one of the transverse partitions between the segments of an annelid
2. : one of the radial calcareous plates projecting into a calyculus of a coral