RHACHIS
Noun
rhachis (plural rhachises or rhachides)
Alternative spelling of rachis
Source: Wiktionary
Rha"chis, n.; pl. E. Rhachises, L. Rhachides. Etym: [See Rachis.]
[Written also rechis.]
1. (Anat.)
Definition: The spine.
2. (Bot.)
(a) The continued stem or midrib of a pinnately compound leaf, as in
a rose leaf or a fern.
(b) The principal axis in a raceme, spike, panicle, or corymb.
3. (Zoöl.)
(a) The shaft of a feather. The rhachis of the after-shaft, or
plumule, is called the hyporhachis.
(b) The central cord in the stem of a crinoid.
(c) The median part of the radula of a mollusk.
(d) A central cord of the ovary of nematodes.
Source: Webster’s Unabridged Dictionary 1913 Edition