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rachis

American  
[ray-kis] / ˈreɪ kɪs /
Or rhachis

noun

  • rachises,
    plural
  • rachides
    plural
  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 British  
/ ˈreɪkɪs /

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

rachis Scientific  
/ rā′kĭs /
  • rachises
    plural
  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.


Other Word Forms

Derived Forms

Inflected Forms

Nouns

Etymology

Origin of rachis

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

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

Each leaflet may have its own stalk, but is attached to the rachis.

From Textbooks ● Jun. 9, 2022

In all modern feathers, the central shaft or rachis is a hollow tube.

From Science Magazine ● Dec. 14, 2018

The finding suggests that the barbs and barbules evolved before the rachis in feathers.

From New York Times ● Dec. 8, 2016

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 ● Dec. 8, 2016

Using my HB pencil, I work to sketch out the barbs of the feather, drawing lines from the rachis outward.

From "Red Flags and Butterflies" by Sheryl Azzam

Sometimes at the base of the rachises, main or secondary, glandular streaks are seen as in the rachises of Sporobolus coromandelianus.

From A Handbook of Some South Indian Grasses by K. Rangachari

The female inflorescence is a large globose head consisting of short spikelets articulate at the very base of the rachis, short bracts and very long, spreading, rigid rod-like rachises.

From A Handbook of Some South Indian Grasses by K. Rangachari

Many species of Andropogon have such jointed rachises.

From A Handbook of Some South Indian Grasses by K. Rangachari

The inflorescence is a spike-like panicle, with very short filiform inarticulate branches and rachises.

From A Handbook of Some South Indian Grasses by K. Rangachari

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