Category:Rhachis

Rha"chis, n.; pl. E. Rhachises, l. Rhachides. Etym: [see rachis.] [written also rechis.]

1. (anat.)

Defn: 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.