\Col`u*mel"la\, n. [L., dim. of columen column. See
{Column}.]
1. (Bot.)
   (a) 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.
   (b) A columnlike axis in the capsules of mosses.
2. (Anat.) 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.
3. (Zo["o]l.)
   (a) The upright pillar in the axis of most univalve
       shells.
   (b) The central pillar or axis of the calicles of certain
       corals.