[ rey-kis ]
/ ˈreɪ kɪs /

noun, plural rha·chis·es, rhach·i·des [rak-i-deez, rey-ki-] /ˈræk ɪˌdiz, ˈreɪ kɪ-/.

Definition for rhachis (2 of 2)


or rha·chis

[ rey-kis ]
/ ˈreɪ kɪs /

noun, plural ra·chis·es, rach·i·des [rak-i-deez, rey-ki-] /ˈræk ɪˌdiz, ˈreɪ kɪ-/.

  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.
Ornithology. the part of the shaft of a feather bearing the web.
Anatomy. spinal column.

Origin of rachis

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


ra·chid·i·an [ruh-kid-ee-uh n] /rəˈkɪd i ən/, ra·chi·al [rey-kee-uh l] /ˈreɪ ki əl/, ra·chid·i·al, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for rhachis

British Dictionary definitions for rhachis (1 of 2)

/ (ˈreɪkɪs) /

noun plural rhachises or rhachides (ˈrækɪˌdiːz, ˈreɪ-)

a variant spelling of rachis

British Dictionary definitions for rhachis (2 of 2)



/ (ˈreɪkɪs) /

noun plural rachises, rhachises, rachides or rhachides (ˈrækɪˌdiːz, ˈreɪ-)

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

Derived forms of rachis

rachial or rhachial (ˈreɪkɪəl) or rachidial or rhachidial (rəˈkɪdɪəl), adjective

Word Origin for rachis

C17: via New Latin from Greek rhakhis ridge
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

Medical definitions for rhachis

[ rākĭs ]

n. pl. ra•chis•es

spinal column
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for rhachis

[ rākĭs ]

Plural rachises rachides (răkĭ-dēz′, rākĭ-)

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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.