rachis

noun

ra·​chis ˈrā-kəs  ˈra- 

plural rachises also rachides ˈra-kə-ˌdēz 

ˈrā-

1

: an axial structure: such as

a(1)

: the elongated axis of an inflorescence

(2)

: an extension of the petiole of a compound leaf that bears the leaflets

b

: the distal part of the shaft of a feather that bears the web

2

: spinal column

Examples of rachis in a Sentence

Recent Examples on the Web

The bristle feathers that typically occur on the face and may serve protective and sensory purposes meld the flight feathers’ stiff shafts (called rachises) with the down feathers’ fluffy base. —Michael B. Habib, Scientific American, 16 Apr. 2024

The primary feathers on older woodcock are also less symmetrical than those on younger birds, with one wider edge on the outside of the rachis, or centerline. —Matthew Every, Field & Stream, 18 Oct. 2023

It is sometimes referred to as the rachis. —Rita Perwich, San Diego Union-Tribune, 5 Feb. 2022

There are also barbules that branch off directly from the rachis, in between points where the barbs branch off. —Gemma Tarlach, Discover Magazine, 8 Dec. 2016

Word History

Etymology

New Latin rachid-, rachis, from Greek rhachis; akin to Greek rhachos thorn, Lithuanian ražas dry twig, tine

First Known Use

1785, in the meaning defined at sense 1