Columella

from The Century Dictionary.

• noun A little column.
• noun 2.In botany: In many cryptogams, especially in Musci, as Mucorini and Myxomycetes, a central axis in the spore-case, a continuation of the pedicel. The spores are arranged about it, and in the Myxomycetes the capillitium branches from it.
• noun The persistent axis of certain capsules, from which the edges of the valves break away.
• noun The carpophore in Umbelliferæ, the continuation of the axis bearing the two halves of the fruit.
• noun In Zoöl. and anatomy: The upright pillar in the center of most of the univalve shells, round which the whorls are convoluted. See cut under univalve.
• noun A bone of the tympanic cavity or middle ear in birds, most reptiles, and some amphibians, corresponding to the stirrup-bone or stapes of mammals; the columella auris.
• noun A bone of the side of the skull of some reptiles, especially lizards, a peculiar dismemberment of the pterygoid, which may meet the parietal or a process of it; the column-bone; the columella cranii.
• noun The modiolus or central axis of the cochlea in mammals, round which the lamina spiralis winds; the columella cochleæ
• noun A core of connective tissue in crinoids which occupies the central cavity included by the coil of the alimentary canal.
• noun A structure in the center of the visceral chamber of corals, typically a calcareous rod which extends from the bottom of the chamber to the floor of the calice, projecting upward in the latter, and with which the primary septa are usually connected.
• noun One of the rods attached to the hyomandibular capsule of the urodele amphibians, representing a remnant of a branchial arch.
• noun A process in the chitinous mandibles of polyzoans.
• noun In human anatomy, an old name of the uvula.

from the GNU version of the Collaborative International Dictionary of English.

• noun 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.
• noun A columnlike axis in the capsules of mosses.
• noun (Anat.) A term applied to various columnlike parts.
• noun The upright pillar in the axis of most univalve shells.
• noun The central pillar or axis of the calicles of certain corals.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a small column (or structure resembling a column) that is a part of a plant or animal