means The series of small bones that stack to form your backbone, each one ringed to shelter and protect the spinal cord running through them.

from From Latin 'vertebra,' meaning a joint or something that turns, built on the verb 'vertere' — to turn — the same root that gives us 'vertigo,' 'reverse,' and 'versus.' The Romans named the bone for what it does: it lets the spine bend and pivot, a column of little turning-points. 'Vertebrae' is simply the Latin plural, carried into English unchanged.