backbone vs grit

backbone and grit both are nouns.

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

As nouns, backbone and grit are synonyms defined as:

Other synonyms of backbone include gumption, guts, moxie, sand.

backbone (noun)	grit (noun)
the part of a network that connects other networks together	fortitude and determination
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	a hard coarse-grained siliceous sandstone
fortitude and determination
the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
a central cohesive source of support and stability

backbone (verb)	grit (verb)
	clench together
	cover with a grit