[
Eh-peen] (n. f.) Stretch your imagination a bit and consider the skeleton, piece by piece, like a botanist might: the larger bones (
humerus, tibia) become tree trunks, smaller bones (
carpals, phalanges) are branches, the skull (
cranium) could be the bulb of a flower, and so on.
In this way, the spine would be the
thorny stem of a flower. That seems like a stretch. Well, tell that to your ancestors who took the French word for
thorn, épine—which was originally spelled
éspine—to make up the word
spine, meaning
thorn-like part.