rachis

American  

[rey-kis] / ˈreɪ kɪs /

Or rhachis

noun

plural

rachises, rachides

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.

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rachis British  

/ ˈreɪkɪs, ˈreɪkɪəl, rəˈkɪdɪəl /

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. another name for spinal column

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rachis Scientific  

/ rā′kĭs /

plural

rachises

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.

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Other Word Forms

• rachial adjective
• rachidial adjective
• rachidian adjective

Etymology

Origin of rachis

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

Example Sentences

“The thickness of the rachis in some specimens is 3 microns thick. That’s less than the size of the average cell,” O’Connor says.

From Science Magazine

It had a magenta rachis down the center with soft green vanes that shimmered yellow and purple and blue depending on how you turned it.

From Literature

But this specimen lacked the rachis; it just had barbs and barbules down its ribbonlike tail.

From New York Times

Their structure suggests that the two finest tiers of branching in modern feathers, known as barbs and barbules, arose before the rachis formed.

From BBC

Fruit.—Fleshy, coalescent and sunk in the rachis.

From Project Gutenberg

Related Words

• bone
• vertebrae