rachis

noun
ra·​chis | \ˈrā-kəs, ˈra- \
plural rachises also rachides\ ˈra-​kə-​ˌdēz , 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

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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The first known use of rachis was in 1785

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