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 rachides (audio) , ˈrā-​ \

Definition of rachis

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

Examples of rachis in a Sentence

Recent Examples on the Web Unlike in other shiny birds, such as hummingbirds or crows, the cassowary's glossiness is produced by the rachis, or the spine of the feather, rather than the barbules, or minute filaments fringing a feather. Katie Hunt, CNN, "How the world's most dangerous bird got its unique feathers," 13 May 2020 Current dinosaur feather fossils don't have a rachis; instead, the specimens show that dinos' feathers acted as a layer of warmth to protect against the elements. Daisy Hernandez, Popular Mechanics, "The Sexiest Dinosaurs Learned How to Fly First," 5 Aug. 2019 According to Persons, flight feathers found on bird wings contain a hollow center called the rachis, from which the barbs protrude. Daisy Hernandez, Popular Mechanics, "The Sexiest Dinosaurs Learned How to Fly First," 5 Aug. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rachis.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of rachis

1785, in the meaning defined at sense 1

History and Etymology for rachis

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

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Time Traveler for rachis

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The first known use of rachis was in 1785

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Cite this Entry

“Rachis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rachis. Accessed 13 Aug. 2020.

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