Iirc, for those interested, it's actually a mistranslation of the original Hebrew term.
The original term is tzelas, which is a bit ambiguous.
It could be rib, but no real way of knowing.
https://www.reddit.com/r/AskHistorians/comments/1321fhe/comment/ji30zz0/
Funnily enough, that is a keyword in rust.
(it's a placeholder to remove any bikeshedding)