Rhachis /(?)/

Rha·chis

Rhachis

n.

pl. Rhachises, Rhachides

  1. The spine. (Anat.)
  2. The continued stem or midrib of a pinnately compound leaf, as in a rose leaf or a fern. (Bot.)
  3. The shaft of a feather. The rhachis of the after-shaft, or plumule, is called the hyporhachis. (Zool.)