connexion vs backbone

connexion and backbone both are nouns.

Word	Noun	Adjective	Verb	Adverb
connexion	Yes	No	No	No
backbone	Yes	No	No	No

As nouns, backbone is a hyponym of connexion; that is, backbone is a word with a more specific, narrower meaning than connexion:

connexion (noun)	backbone (noun)
the act of bringing two things into contact (especially for communication)	the part of a network that connects other networks together
shifting from one form of transportation to another	the part of a book's cover that encloses the inner side of the book's pages and that faces outward when the book is shelved
an instrumentality that connects	fortitude and determination
the process of bringing ideas or events together in memory or imagination	the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
a relation between things or events (as in the case of one causing the other or sharing features with it)	a central cohesive source of support and stability
a connecting shape