n. - An axis to which a carpel of a compound pistil may be attached, as in the case of the geranium; or which is left when a pod opens.
n. - A columnlike axis in the capsules of mosses.
n. - A term applied to various columnlike parts; as, the columella, or epipterygoid bone, in the skull of many lizards; the columella of the ear, the bony or cartilaginous rod connecting the tympanic membrane with the internal ear.
n. - The upright pillar in the axis of most univalve shells.
n. - The central pillar or axis of the calicles of certain corals.