rachis

or rha·chis

[ rey-kis ]

/ ˈreɪ kɪs /

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

Botany.

the axis of an inflorescence when somewhat elongated, as in a raceme.
(in a pinnately compound leaf or frond) the prolongation of the petiole along which the leaflets are disposed.
any of various axial structures.

Ornithology. the part of the shaft of a feather bearing the web.

Anatomy. spinal column.

Nearby words

rachilysis, rachio-, rachiocentesis, rachiometer, rachiotomy, rachis, rachischisis, rachitic pelvis, rachitic rosary, rachitis, rachitogenic

Origin of rachis

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

Related forms

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. 2019

British Dictionary definitions for rachial

rachis

rhachis

/ (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

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

Medicine definitions for rachial (1 of 2)

rachial

[ rā′kē-əl ]

adj.

Rachidial.

Medicine definitions for rachial (2 of 2)

rachis

[ rā′kĭs ]

n. pl. ra•chis•es

spinal column

Science definitions for rachial

rachis

[ rā′kĭs ]

Plural rachises rachides (răk′ĭ-dēz′, rā′kĭ-)

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.