Rhachis
Rhachis , noun
[See Rachis.]
1.
(Anatomy) The spine.
2.
(a) (Botany) The continued stem or midrib of a pinnately compound leaf, as in a rose leaf or a fern.
(b)
(Botany) The principal axis in a raceme, spike, panicle, or corymb.
3.
(a) (Zoology) The shaft of a feather. The rhachis of the after-shaft, or plumule, is called the hyporhachis.
(b)
(Zoology) The central cord in the stem of a crinoid.
(c)
(Zoology) The median part of the radula of a mollusk.
(d)
(Zoology) A central cord of the ovary of nematodes.