Other forms: spines
The spine is the line of bones down the middle of your back. A curved spine, an injury to the spine, feel it in your spine.
Backbone is the everyday word and spine the medical one. A book's spine is the edge that faces out on a shelf and carries the title, which is one of the commonest uses of all. In plants and animals, a spine is a sharp point — a cactus spine, a hedgehog's spines. And figuratively, the spine of something is its central supporting part: the spine of the argument, a spine of hills.
1nounspineThe line of bones down the middle of the back.
“The injury was low down the spine.”
synonyms: backbone, vertebral column
2nounedgeThe edge of a book where the pages are bound.
“The title on the spine has faded to nothing.”
3nounsharpA sharp point on a plant or animal.
“The spines come out easily enough if you are quick.”
spine is a backbone or sharp point.
Also accepted in games: backbone
Latin spina meant a thorn first and a backbone second, named by the resemblance to a row of thorns. English took both senses at once, which is why a cactus and a person can each have spines with no metaphor involved.
Proto-Indo-European
*spey-
Latin
spīna — a thorn; a prickle, spine; the backbone
Old French
espine
Middle English
spyne
English, today
spine
From late Middle English spyne, from Old French espine (French épine) or its source, Latin spīna (“a thorn; a prickle, spine; the backbone”). a doublet of spina.
Etymology from Wiktionary, CC BY-SA