Rhachis

Definition:

(n.) The spine.
(n.) The continued stem or midrib of a pinnately compound leaf, as in a rose leaf or a fern.
(n.) The principal axis in a raceme, spike, panicle, or corymb.
(n.) The shaft of a feather. The rhachis of the after-shaft, or plumule, is called the hyporhachis.
(n.) The central cord in the stem of a crinoid.
(n.) The median part of the radula of a mollusk.
(n.) A central cord of the ovary of nematodes.

Compare rhachis with other words:

rhachidian vs. rhachis