rachis
noun
ra·chis ˈrā-kəs 
ˈra-
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
Example Sentences
Recent Examples on the Web Just like canes, the petiole or rachis is covered with an epidermis and may grow tiny prickles along its underside. 
Rita Perwich, San Diego Union-Tribune, 5 Feb. 2022 Larger feathers consist of a shaft (the rachis) bearing branches (barbs) which bear smaller branches (barbules). Jim Williams, Star Tribune, 25 Aug. 2020 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, 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, 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, 5 Aug. 2019
Rita Perwich, San Diego Union-Tribune, 5 Feb. 2022 Larger feathers consist of a shaft (the rachis) bearing branches (barbs) which bear smaller branches (barbules). Jim Williams, Star Tribune, 25 Aug. 2020 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, 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, 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, 5 Aug. 2019 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