ra·​chis ˈrā-kəs How to pronounce rachis (audio) ˈra- How to pronounce rachis (audio)
plural rachises also rachides ˈra-kə-ˌdēz How to pronounce rachis (audio)
: an axial structure: such as
: the elongated axis of an inflorescence
: an extension of the petiole of a compound leaf that bears the leaflets
: the distal part of the shaft of a feather that bears the web

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 Like those of modern birds, these feathers had two asymmetrical vanes coming off a central shaft or ‘rachis’. Ed Yong, Discover Magazine, 13 May 2010 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 From its main shaft, called the rachis, thousands of filaments called barbs branched off. Carl Zimmer, Discover Magazine, 18 Jan. 2011 In stage three, the barbs partially unite to form a central rachis, and even smaller filaments called barbules start to branch off from the barbs. Discover Magazine, 12 Sep. 2011 Feathers from the amber specimen also have a rachis, barbs, and barbules. Gemma Tarlach, Discover Magazine, 8 Dec. 2016

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'rachis.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

Time Traveler
The first known use of rachis was in 1785

Dictionary Entries Near rachis

Cite this Entry

“Rachis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rachis. Accessed 25 Jun. 2024.

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!