rachis

or rha·chis

[ rey-kis ]

noun

, plural ra·chis·es, rach·i·des [rak, -i-deez, rey, -ki-].

1. Botany.
   1. the axis of an inflorescence when somewhat elongated, as in a raceme.
   2. (in a pinnately compound leaf or frond) the prolongation of the petiole along which the leaflets are disposed.
   3. any of various axial structures.
2. Ornithology. the part of the shaft of a feather bearing the web.
3. Anatomy. spinal column.

rachis

/ ˈreɪkɪs; rəˈkɪdɪəl; ˈreɪkɪəl /

noun

1. botany the main axis or stem of an inflorescence or compound leaf
2. ornithol the shaft of a feather, esp the part that carries the barbs
3. See spinal column
   another name for spinal column

rachis

/ rā′kĭs /

, Plural rachises răk′ĭ-dēz′,rā′kĭ-

1. A main axis or shaft, such as the main stem of an inflorescence, the stalk of a pinnately compound leaf, the shaft of a feather, or the spinal column.

Derived Forms

• rachial, adjective

Other Words From

• ra·chid·i·an [r, uh, -, kid, -ee-, uh, n], ra·chi·al [rey, -kee-, uh, l], ra·chidi·al adjective

Word History and Origins

Origin of rachis¹

1775–85; < New Latin < Greek rháchis spine, ridge, backbone

Word History and Origins

Origin of rachis¹

C17: via New Latin from Greek rhakhis ridge

Example Sentences

The pinnules are from a line to two lines long, and are adnate to the secondary rachis by a more or less decurrent base.

From Project Gutenberg

The stipes is somewhat longer than the rachis, and it is of a whity-green colour.

From Project Gutenberg

A simple inflorescence of flowers on pedicels of equal length arranged on a common, elongated axis (rachis).

From Project Gutenberg

A simple inflorescence of sessile flowers arranged on a common, elongated axis (rachis).

From Project Gutenberg

Under these conditions the midvein is called the rachis (a), and the divisions are called the pinn (b).

From Project Gutenberg

Related Words

• bone
• vertebrae